look up what helmet design rules cover, they are only designed to protect you from near lethal impacts, not mild potentially brain damaging injuries.I understand that the mips is to reduce the rotational forces and in this regard I'm sure it helps but by adding a barrier between the foam and your skull, the same barrier that provides the "slip" for mips you are affecting the way in which the polystyrene is supposed to work.
Each to their own. I'm sure they all protect your noggin, I'm just not convinced that either is better than the other, they each have advantages and disadvantages as I see it, try to look past the marketing.
the idea of mips is to try and improve your chances of suffer an acquired brain injury, watch the youtube video i posted it explains it quite well.
anything that helps protect your head is a good thing.