It takes about 50 Cripple MOABs to destroy a B.F.B instantly.
It takes 50 shots from 50 Cripple MOABs to destroy a whole Z.O.M.G. (Including all that come from it).
Cripple M.O.A.B. towers are worthless in the early rounds because of the lack of M.O.A.B class bloons. However, with a smaller defense the player problably wouldn't be able to upgrade it to this before level 50, when M.O.A.B.'s start coming down more regularly.
The addition to the sniper rifle at the end appears to be a barrel stabilizer.
This is very useful for later rounds with blimps.
A single Cripple MOAB can immobilize a Z.O.M.G. only for half second in fast forward. More snipers will stop the Z.O.M.G for longer.