I think with the helmets that have been on the market for years (non-MIPS), it all depends on the crash. Some people find that the helmet breaks but their head is okay, but in other cases the helmlet does not help prevent serious injury. I think it depends on factors like the type and angle of impact. I recall a few years ago watching a big high-speed crash during a sprint finish at a grand tour. In the replay you could see one rider -- Tyler Farrar I think -- hit the ground and his head bounced off the pavement. The worse injury he suffered that day was a bad cut to his elbow. So that was a case where the helmet worked. Sadly in other cases it does not help. I know people who have looked at the available statistics and concluded that helmets are not worth wearing because they don't really help in a crash.
When I bought my current helmet a few years ago, I had a hard time finding one with lots of big vents AND a visor. Most of the really vented helmets are high-end and the assumption seems to be that only people who wear less expensive helmets with smaller vents want a visor. Eventually I found the Bell Volt, which has worked well for me, so a few weeks ago I thought about getting another one. Then I thought, maybe I should look for one of those MIPS helmets instead. There's nothing wrong with the current helmet so I haven't looked further into the MIPS helmets that are currently on the market.
- Gray 2010 carbon WSD road bike, Rivet Independence saddle
- Red hardtail 26" aluminum mountain bike, Bontrager Evoke WSD saddle
- Royal blue 2018 aluminum gravel bike, Rivet Pearl saddle
Gone but not forgotten:
- Silver 2003 aluminum road bike
- Two awesome worn out Juliana saddles