Also, one thing to clarify.
MIPS deals only with torsional impact (twisting), FLEX deals with that plus lots of extra standard kinetic impact protection.
It all comes down to how well you want to protect the rider's brain. more padding, more distance, softer padding, less twisting -- all off that reduces the
accelerations applied to the brain.
how big can you allow that to become?
I have seen comparisons of consistency between a 20-something's brain and tapioca pudding.
The older you get the more stiff the connections become -- 'hard headed' is really a thing. It's just inside
The initial Snell standard was designed to protect racecar drivers from whacking their heads on the roll cages of their cars. Because the hits could occur in the same place repeatedly the padding had to be quite stiff to protect the skull from that impact.
It was already understood that the # of Gee allowed in that scenario were too high for a healthy brain.
The DOT allowed far less Gee, in their medically based guidance. That requires softer foam, and more of it to allow the liner to crush more gradually.... that spreads the load out over time. deltaV, over delta t.
The newest Snell standard matches the euro requirements, which come very close to matching the initial DOT numbers.
If these technologies are allowing lower number of gee than any of these standards, that can only be a good thing for brain health.