Actual data on helmets is crazy. There's actually several studies that essentially argue that bike helmets are a waste of time (the number of wrecks where the helmet makes a difference is really small because you either die or aren't hurt much at all). Given how easy it is to wear a helmet I think that logic is silly because if you are in the crash the helmet would help who really cares how rare it is.

I feel similarly about MIPS. My next helmet will probably be a MIPS helmet unless the helmet is uncomfortable. Will it make a difference? Who knows, but why not? Now if another helmet has a feature you want or if you don't want to pay the increased price for a MIPS helmet I wouldn't worry about it. If those things aren't a big deal then the MIPS seems worth it to avoid a brain injury even if it's extremely rare.