5s with mm ?

It really depends. Some will do it and some won't. Those that will do it, from what I've seen, run ok with mild gearing. If you get too heavy on the gearing, it will start cogging. If it does, back off of the gearing.

Although I do treat my MM controllers badly, I did blow up four or five of them running 5S. Even if you can get away with it, you would be better off with a proper controller. Many have been having success with the Compro line of controllers.