I wouldnt use ANY Nimh batteries with the MMM combo , it will draw way too much current and will cook NiMh batteries .
NiMh batteries can be almost as dangerous as LiPo if overworked , there is a vid on youtube of a kid running a STOCK E REVO doing wheelies and drifting in his driveway , well after a bit you hear this bang ! and his car stops running , turns out one of the cells in his NiMh pack blew up
It blew the door open on the battery compartment and shot the end of the battery out the side of the truck . Here is the vid ...
The MMM combo draws even more current than the stock system so run them at your own risk (I wouldnt)
As cheap as LiPo and DECENT LiPo chargers are getting there really is no reason NOT too go LiPo . As long as you use them the way they are intended to be used they are JUST as safe as any other batteries IMO .