I've got the trunk plus and have flown UA, NH, TK, AI, TG, with it. No one has ever given it a second look.

The only "issue" with the trunk plus is that it really does take an enormous loaf of stuff exceptionally easy. So there is the danger of being over the weight limit before the bag j's full. I use it on journeys of 1-3 months and where I'll definitely bring back a lot of stuff.

Unless you really need all that space all the time, I think most would do better with the regular trunk because it's more likely ro stay near the weight limit when fully or over packed.