Greetings! Good question on the B&R, I have read mixed stuff on the posts as well. I have the 21.5" B&R baseline, and it is not 21.5" handle to wheels, but a tad longer. Haven't measured exactly but it's a big shorter than my 22" Travelpro which is 23.5", and I have not had problems with that one, albeit it's always been on 757, 777, 747, but have not taken it on smaller aircraft, 737s, A319s, etc.
If I could do it over again I would get the 20" B&R baseline but the "international" or "lightweight" version. The pluses I see with that one are 1) it is not expandable (at least according to website) so you don't have that flap of extra material inside and 2) it's ~100 bucks less than the expandables. This version still has a suiter compartment as well.
Other folks have posted that the exterior handles on the carryon sized B&R take up valuable packing space for a carryon. However, I prefer the flat packing surface. But that's a matter of personal preference.
Good choice on B&R, quality product and great warranty. I started with Travelpro but migrated to B&R and Red Oxx -- the quality and functionality are well worth the price. Good luck!