I've got a pretty ok carry-on, but it's made out of a heavy vinyl type material. Mostly I just travel with an old army knapsackl though if the trip is short. Last year I was walking past a luggage display and I reached out and lifted one of the ultralights. Holy hell are those things light. It felt like I was lifting a Sunday edition of the New York Times.

Since then I've been mentally weighing the return on investment I'd get by buying a new ultralight carry-on vs just using what I've got, since I travel kind of a lot. Like thenewgreen, I refuse to check bags because there is only a downside. With more and more airlines putting a weight limit on carry-on after which a charge is triggered, the lightest possible container makes sense, esp when you are fitting all of your gear for your trip into it.

I'm thinking a beat up used ultralight would be the best of all worlds, because even though it will be with me at all times as a carry-on (hopefully), I'm a huge proponent of carrying used/shitty looking items when they are ripe targets for theft. My knapsack has one shoulder strap that is broken and no longer adjustable. It's knotted together, which I approve of; it looks like the last place you'd find anything of value...good to carry my laptop because it doesn't telegraph having a laptop pocket or anything like that. That being said, a lot of thieves are just idiots who will grab anything.