diletante,
D2 or M2 would be better edge-wise, yes, but they can't match VG-10 in corrosion resistance. Also D2 and M2 aren't quite as fine as VG-10.
For whatever it's worth, I've handled almost all axis locks except for the Griptilian (The mini-griptilian felt crappy enough!) and the Axis TSEK/Axis AFCK (But i've handled a regular AFCK, which felt great), i've also never handled a BM 770 but with my size hands, it would've been a waste of time.
For me there are 4 knives that stand out in the ergo department: 721, 730, and the 806D2/805.
Basically from what i've heard here is that without D2 or M2, pretty much all BMs are created equal cutting-wise. Unfortunately i'm one of those who has alot of trouble coming to grips with BT2, and as such, I cannot find myself enthused about the 806D2 (if it were satin it'd be the easy choice).
I'm thinking seriously about the 730.