I'm not MIPS fan. There is no standard test for the spin injury it is designed to protect against. The MIPS own test requires that the helmet is strapped on tight to have any effect. Apparently, if you leave the helmet loose (the way we all do IRL) there is no difference between MIPS and non-MIPS helmets. I'm thinking that the non-MIPS helmet just spins on your head and protects you against the rotation injury as well as MIPS does.
When Snell or ASTM comes up with a standard test for rotation injuries, I'll look for a helmet that protects me from that.
dm