I am spoiled. My main roll-aboard bag that meets carry-on sizing is an older Osprey Vector 22, which (sadly) they don't make anymore. It's an almost perfect bag and in great shape, which is why my wife wants something similar and we tried out the Osprey Ozone.

The Ozone is a good bag, but it's not GREAT. The frame system is different than the Vector, and it doesn't have as much room inside. (The Vector's awesomeness is that it is so soft that it still fits into nearly every airline's carry-on sizer.) The T-handle is also a pain in the neck, because there's no leverage if the bag hits a rough spot (European cobblestones in streets and sidewalks, yo) and starts rocking back and forth. It'll just twist until it falls over.

I also am not a fan of the wheels Osprey uses. I switch them out right away for slightly softer rollerblade or scooter wheels.

The Ozone also has slightly weird compression straps in the corners that you have to unbuckle every time you want to get into the bag. The top pocket is sized weird and doesn't work as well for your 1-liter bag of liquids (which was a genius addition to the Vector back when it came out).

Finally, the way the internal pockets' zippers are placed is weird and harder to get into than they should be, as well as the back pocket not being very useful.

Frankly, I compare every roll-aboard to the Vector, and that bag is so terrifically awesome that everything comes up lacking. I'm going to give the Rolling Transporter a try and hopefully it'll go better, but I'm not optimistic.