I actually tried bépo for a week or two...
Since I'm no touch-typist, learning bépo was even more harder, to the point where I dropped it altogether.
After all, I don't type that much, and when not typing heavily, I'm having only one hand on the keyboard (just in case: the other in on the mouse, mkay ?), so I don't see myself put both hands on just to feel the nubs and type one or two keys.
Having a bépo layout on keys would then help, but that's another story.
As crappy as AZERTY may be, when you've used it all you life, well, you use it.
Regarding going US-international... I'd probably miss the accents (I don't remember the specifics of that layout though... and am too lazy to look it up).
Not using capitalized diacritics, a mistake ?
Most probably, but to be honest, whatever text I come across, there's a good chance they're not used, so no big deal.