The extra 2L is just the front pocket.
I just like the look of the 22L better and the 20L I believe has these umbrella holder straps on the side that I would never use. But the 20L is incredibly popular too, so it's quite subjective.
Use mine just about everyday, can't foresee any durability issues.
measurements would mess you up on the bomber anyways. it's ever so slightly padded.
all measurements i saw had something like 19" shoulders and 24" chest on a 48, except when I got it, it fit exactly TTS.
get the virgils man. If there is still something available in your size, get it man. it's a really nice makeup they just released. not sure how you don't have a pair already, considering your collection...