I think it’s like taking more vitamins than the daily recommendation. You could be preventing a cold or helping recovery or you could be making expensive pee.
We don’t exactly know how much safer these technologies are. But having seen the effects of a TBI I know I’d do my best to prevent one. Everyone can skew their data to make it look better than someone else’s (yaw angles in a wind tunnel or picking the best data when the wind is swept is common practice in aero marketing) but I’m pretty impressed with what I’ve seen for WaveCell. Is it better than MIPS? I dunno. Standardized testing protocols for this stuff along with publishing the data in a national repository would be amazing but that’s not going to happen.
One MFG once published their data and said that their helmet was safer. Unfortunately someone still got injured and sued that company. Now MFGs are scared to publish data because that opens them up to legal issues.
Finally, unless you have an engineering degree (I don’t) it’d be pretty difficult to look at the testing data and say that one helmet is definitely safer than another. e.g. one brand might test 2x better for frontal impact and another might test 3x better for side impact and yet a 3rd might test 4x better for rear impact but 1/3 as good with front impact and 1/2 as good with side impact. Which one is better?
At that point you really need to decide what kind of crash you’re gonna have and choose the helmet that fits that crash.
This goes to what I was saying above. I wish I could tell you.
If you plan on getting hit by a car and dragged 50 feet I’d suggest a hardshell helmet. If you plan on falling off the bike and hitting a rock with your occipital lobe, then go for something with more rear coverage. If you plan on crashing on some rebar maybe go with something that has less vents.
If you want the safest . . . maybe choose the helmet with thickest foam everywhere. You’ll look like a mushroom and won’t be aero but you’ll be a bit safer.
I honestly wish I could give definitive answers but even if we tested every point on a helmet in a lab there’s no telling if your crash (everyone’s number will be picked one day) will be anything like the tests.