BD, we care!
Most of us would consider two key factors:
A)- are you going to gig with it?.....and
B)- how much money is each option?
I highly recommend the M3...(without the dorky solid-state Leslie 700 that makes it sound, uh, castrated).
These under-rated little (relatively speaking) gems can wail, scream, purr and smoke with the best of 'em when you put it through a good old TUBE Leslie, meaning a 145, 147, 122, or 142.
You should be able to get the M3 for peanuts. Chances are the Leslie and the hookup for it will be the bulk of your outlay.
1)- It's half the weight of the BV or C2.
2)- It has all the main ingredients of the B3 that we crave: 2 keyboards (with a full set of drawbars for each), complete 4-rocker-tab percussion section, AND vibrato Chorus (sorry, Steve
One possible limiting factor with the M3 might be the fact that both keyboards only go down to the F, rather than the lower C.
Personally, I find that this actually helps in keeping out of the bass player's musical territory. You can still chord and rhythmatate (?) like crazy with your left hand on the lower keyboard, while finger-dancing, shredding, and generally laying it down with your right on the upper.....Yeah!
P.S.- it makes for a wonderfully stable and ergonomically pleasant platform for any other portable keys you'd like in front of you (especially a digital piano).