For safety, generally there seems a lack of much real assessment as to how helmets deteriorate over time.
The only info rhat was ebem half scientific was a few years ago by Met.
I recall they came up with something like 7or 8 years (or obvs a crash, which ever 1st).
Unless from the 80s the foam is supposed to be UV stabilised.
Myself… i get a bit nervous beyond about 5 years. And I’m pretty careful with the helmet in transit etc.
For MIPS… I’m yet to be convinced.
Fine the test dummies show improvement - but the tests never seem to reflect the benefit of hair and skin which also gives a lot of shear / movement - put your hand on your head and feel it move w.r.t. your skull. If that moves 10mm and MIPS say 5, the claims made seem overly stated vs a neigh on rigid test head.