Has anybody actually used the TB packing cube backpack and/or their packing cube shoulder bag?

They look like more of a "carry my stuff from the hotel to the meeting room or restaurant option" rather than an actual daypack.

I'm trying to figure out how to economize space and weight more by eliminating an actual daypack for tourist uses, e.g. extra clothes, food, camera, etc. I'm guessing that without padding for the backpack straps, they really aren't that usable. If that is the case, would adding padding improve it? I travel with these pads anyway:
http://www.amazon.com/National-Geographic-NG-A7300-Shoulder/dp/B003WE9MPU

I should probably just get the Synapse 19 or 25 and call it a day.

I have a Synapse 25 ordered - well actually back ordered until late June for the colour combination I want. I like the look of the packing cube back pack but could not really see it replacing a few other day-type bags I already have. I know that does not answer your question but could not ignore the mention of the Synapse 25 - I am looking forward to it as I get better at packing quite light.

I once asked the lovely people at Tom Bihn about how much weight the Packing Cube Packpacks could comfortably carry and the response was definitely no more than about 5kg (which I took to mean I should expect some discomfort with that sort of load). I have a Synapse 19 and I just got a Synapse 25 (which I haven't used yet). Personally I would choose the 19 as a small but efficient daypack solution despite the space/weight compromise. You get, IMHO, superior compartment organisation with the Synapses (versus no organisation with the PCBPs). But even if you get one in nylon/dyneema, you don't save that much weight or bulk because of the straps and back padding etc.

As far as I can ascertain, the biggest drawback to the TB packing cube/backpack is the material is so thin. Because of this, it has no form when loaded and offers little protection to the contents. This would be true of any packable backpack/messenger bag as well.

That's why I was thinking of resigning myself to losing the packing space and weight and just getting something like the TB Synapse.

I have the Packing Cube Shoulder bag and have used it as a packing cube and then day bag. It does not have any structure to it at all and doesn't offer any protection. I've used as a packing cube in my TLS Motherlode and then as a day bag and it serves its purpose. I don't mind it as a day bag although it isn't my first choice. It does work though if space is limited, you can only have one bag on the plane, and you need just a basic day bag. I think it works for exactly how it is intended...not to be anything fancy or super organized, but can be used to carry the odd items around in. I like mine, but I can also see where it wouldn't work for some people. Hope this helps. YMMV.

I have the Packing Cube Shoulder Bag and had hoped to use it as you propose. But it's so floppy there is no way I would use it to carry to a meeting or restaurant. It looks like a packing cube with a strap attached and has absolutely no stiffness to it to maintain any form. If I was on vacation and just needed something to put a guide book and my camera in for the day, then maybe, but it is definitely not a purse substitute. I just use it as a packing cube and bring along a small lightweight purse that packs small. Or if I am lucky enough to have pants with good pockets, I don't even bring the purse.

I bought an Packing Cube Backpack (Aeronaut) about a month ago. I am gearing up for a trip to Slovenia towards the end of summer. Not so much for a day bag. It is insurance that I'll be able to have enough room coming home. I am "Grannie" to two wonderful kids, and I do buy things for them on all my trips. I must say I'm was somewhat perplexed on how to pack it in the packing cube mode at first. The Tom Bihn website shows it being turned inside out to use in the packing cube mode. But, I was unclear if I was supposed to pack the bottom compartment also. Then it dawned on me! Hey! Its mine! I can pack it anyway I want too! I love that I have options depending on my need.

I have the Tri Star packing cube backpack and love it. I use it in situations where I think that I might need to carry stuff around later in the day. For instance, I was on a temporary work assignment last year where I lived about a 1/2 mile walk from work, in a 4th floor apartment with no elevator. There were lots of grocery stores and shops near the office so I often stopped for groceries on my way home. I would carry the backpack to work empty then use it to carry my groceries in the evening. It would fit about the same as 1 or 1.5 plastic grocery bags but was much more comfortable than carrying the bags by hand for that distance. I do the same when I visit my parents and we take the bus around. I bring the empty backpack in case we buy items that we need to bring home later. Because the bag has no structure, I don't feel the empty bag at all when I have it on my back. The backpack material is fairly strong considering how thin and light it is -I had no problems even when it was full of groceries, including milk, canned goods, etc. While padded straps would have been more comfortable, I didn't find it too bad, especially compared to how uncomfortable it would have been to carry plastic grocery bags for a 1/2 mile and then up 4 flights of stairs!

I have one. I have used it as a gym bag for the short walk from work to gym, but it is a little awkward for other activities since there isn't a lot of structure, and things fall to the bottom of the bag. For example, retrieving my wallet can be tricky.

I like it as a packing cube that can serve as an emergency bag if needed. I might put my most important clothes in it, if there was a chance my bag might get checked, and then I could pull it out and keep it with me during the flight should that occur. Or I would use it as a secondary bag if I needed more space in my main bag. But I don't think I'd regularly depend on it as a day pack.

OK. I have a Western Flyer, which is one of the best purchases I've ever made, so it makes sense to give the mated packing cube/backpack convertible a try. At the very least, I can use it like bchaplin.

I'm still going to get a Synapse; I'll just troll around waiting for a "previously enjoyed" one.

I have used it a lot from shopping to biking. I don't mind the lack of structure and it adds a great deal of flexibility to my Western Flyer. I would rate it as a very good purchase.

I love the packing cube backpack! I always pack when I travel and always end up using it for something: as a day pack for hikes, carrying my gear around town, hauling groceries. It is kind of floppy and not super stylish but it totally works. It seems like the straps would be uncomfortable but they're not, even with a heavy load.

I use the Packing Cube Backpacks, both for Aeronauts and Tristars/Western Flyers, with a Brain Bag on domestic (U.S) flights, car and train trips.
And, in Europe, with my Aeronaute and Tristar.

The organization they provide is the most efficient given their capacity/weight ratio.

They are great to protect against hotels' grubby dresser drawers.

In a pinch, they also serve as extra ultra light bags.

The Packing Cube Shoulder Bag was used to pack small stuff for an assignment out of town.
I had to attend an event in a third town, over the weekend, in the middle of the assignment.
I forgot to bring a small purse, the Steel Packing Cube Shoulder Bag was put in service for the dress up dinner.

The Packing Cube Backpacks are wonderful for organizing different wardrobes, in a minimalist manner.
One Cube can hold casual wear and the other nicer clothes.
At present, Tom Bihn offers 4 Dyneema colors which is wonderful for color coded packing organization.

The Packing Cube Backpack was used as a secondary bag on a short sightseeing cruise. It was adequate for that and very useful to transport groceries.

I still recommend the Synapse 19 for a daypack, a Shop Bag for shopping and a Kit, which fit in the lower pocket of the Synapse 19, and, can serve as cute purse backup, in the evening.

It works great for cruising. I take it into port to carry whatever we buy and usually use a single strap over the shoulder. It helps keep purchases/etc out of rain. It is floppy but maybe that will encourage a thief to move on to prettier backpacks.

The Packing Cube daypack(s) - there are two and I have both - work great in just two narrow situations:

(1) You need a packing solution for whatever bag you are using - your other luggage doesn't have to be Bihn! - for a little extra weight, you get a "dual purpose" bag, compared with regular packing cubes. Also, check your weights on your "mesh" cubes like the ones from Steves even the ones from Bihn - mesh fabric is actually usually significantly HEAVIER than solid fabric panels despite all the holes - the material is so much denser. So there isn't as much of a weight penalty with the packing cube daypacks as you may think at first, although the straps DO mean there IS a slight penalty.

(2) The only use I've found for the packing cube as a daypack locally, is for side trips to the beach where I leave my larger, heavier luggage at the hotel - since the daypacks are both very rectangular instead of contoured, they fill VERY well with clothes. The clothes add the structure necessary to prevent bag-sag, for the most part. The straps are more comfortable on my shoulders than, say, the lightweight straps on the Patagonia Lightweight Travel line of messenger bags and packs, and more comfortable than the lightweight straps on the REI Flash 18 and 22. They are basically seat belt material and don't "pinch" compared with lighter webbing straps.

The main problem with the Bihn's is that they don't make very appealing daypacks for local use. They look too flimsy and "traveler" for me - even though they are anything BUT flimsy.

For my use, I like the two compartment version so I can stow my shoes in the bottom to keep them separate from clothing. The single compartment edition (with slash compartment on front) actually has a larger volume, but for my limited use I don't need the extra volume.

If you need a REALLY light, efficiently shaped, pack for carrying into the cabin on an airline with really draconian carryon limits, this is the BEST pack out there. But almost no organization, a floppy material, it WILL sag if you don't pack carefully, and no laptop or iPad padding.

For the same reasons this is a GREAT pack to carry onto a beach-bound 9 passenger mini-van with narrow pitch seats - easy to hold on your lap. Not too fat.