I owned the 705 for about a week. It seemed like a beefy handle with this little blade on it. Yet, the handle was too small for me. The 770 I've only handled in the store, but it's a bit better ergonomically. The axis lock mechanism appears to have been reduced in size so that it seems more appropriate than it does on the 705.
Also, more generally, thumb-stud opening knives have an effective working length (for slicing especially) that is less that their full blade length because the stud gets in the way. I returned my 705 and bought the 940. When I want carry a smaller blade (akin in size to the 705 or 770), I carry my Calypso Jr, which fits nicely in my hand, it's a 4-fingered hold on the handle, whereas the 705 and 770 are 3-fingered for me, and the Calypso has about the same blade length as the 705 and 770.
Now I am not trying to talk you out of the BMs which are fine knives, just presenting you with some of considerations in considering a smaller knife.
Regards,
David