im running a monster termination (i think). its either the mass, or the monster, whichever is faster. and so far, i LOVE it.
OTOH, for 140 bucks you cant beat the mamba for ease of use. on our track at Xtreme RC, the track is so tight and technical that the mamba doesnt really afford an advantage, and the mod brushed guys win (we run them together). but for ease of use and maint., definitely the mamba.