I had a Synthe MIPS. I crashed and cracked it a couple months ago. I replaced it for the non-MIPS version.

I think in theory MIPS makes sense. But I didn't find it useful practice. First, the system created two bumps that dug into my head. I had to glue additional padding into the helmet to cover them. (Note: This was something that affected me. A teammate with a MIPS Synthe did not experience the same issue.)

My second complaint had to do with ventilation. The MIPS basically created a thin plastic shell inside the helmet that I felt made it hotter. It seemed to me that it trapped heat and provided a place for sweat to collect rather than to evaporate out of the helmet vents.

Also, I am looking to add a Protone to my collection in the near future. I don't care that it doesn't have MIPS.