I don't think anyone around here but me uses this particular bag, but I've had one of LL Bean's Quickload roller duffles (medium size) for nearly 13 years, and it's been excellent throughout. I don't think you'll find a bag that holds more for its size, and it's one of the lighter-weight bags in its class (about 6lb). I have never had any trouble carrying it on except on one of the smallest regional planes, but I don't fly Delta. Given LL Bean's attitude to returns, however, there's no reason you couldn't buy the bag, take it to the airport, and test it in the sizer.
With any soft bag, it matters how you pack it. The UK was for a while rather obsessive about measurements and insisting people put their bags in the sizer, so I got in the habit of measuring the bag myself before leaving home.
If I were buying a bag now, I'd weigh up between this one and Eagle Creek's 22in and 20in Load Warriors. Capacity wise, this one would win hands down. The Eagle Creek bags are a shade lighter, probably easier not to overpack, and have some neat features.
wg