Tho the only downfail to mmm is it doesn't have all mmd effects recoded for it. Tho. MMM still runs most of mmd effects just fine. But, unlike mmd if you press select all where the dots are in the upper left. Use edit => bias and move the model. You can make group dancing look smoother than, in mmd. While, you can drag x files when, mmd can't do that.
So if you experiment with mmm a bit more. It's just a better engine. Tho the lighting and, other things like kinnect work so much better. Tho with lyp synch loid and load a 48000 bit rate wav file you can lip sync your model to vocals . Which mmd can't do yet since, it lacks the memory power needed for some things.
But, things like mmm blink you will notice it adds 4 times the blink tha, mmd does. Do it generally looks smoother. Than, having to do mmd blink plugin 4 times XD But, MMM doesn't run grass/ water effects that great sadly. But, you can make camera motions on the fly in mmm. Unlike, mmd where it could take hours to make a camera motion.
So with all of those things MikuMikuPlus has a lot of catching up. If it want's to do as much as MMM can do . But, the user is still doing a great job at it. But, mmd stopped updating on old bullet physics engine stuff. While, MMM was updated last year.