i didnt get on the beta either. i was hoping to.
its hard to compare MB and ZB , since MB is still in beta, and ZB is seeing its 4th release [iirc]
so if the beta of MB is up to par with ZB [2 not 2.5] in terms of raw-poly-pushing and ease of use, i think MB v1.5 or even 2 will eventually surpass ZB albeit they throw in a way to paint models, because as of now its strictly sculpting.
ive seen some awsome works from some of the beta testers though.
for now, i must say i love ZB
although navigating in it still infuriates me at times, but its so efficient and with tons of features