Regarding the overhead storage, we're always being told what the maximum size is. And with loco's we're being educated that you're a burden for bringing checked baggage. On the third hand, one of the problems with this type of aircraft is that one can board with a carryon-sized item for which there is no longer any space. So my suggestion is, a check-in - side check that one's roller case is the correct size, which gives one a chit for an overhead slot on the aircraft. It doesn't matter when you board, that slot will be there. Those with the random-sized packages get to stuff them below the seat in front. One would receive a boarding pass with a seat number and baggage slot number.