Esp. on the variables part.
I think the hardest part is that most of us are wearing stuff we’ve not (yet?) crashed in.
So we base our judgements on relative knowledge of the universe of materials, manufacturer’s claims, other’s reviews, etc., but at the end of the day, it’s hard to know what’s really going to happen until it does.
With cars, seatbelts are seatbelts, and airbags are airbags (though how many does make a difference)…with bikes, there’s always the question of “is Fieldsheer = Alpinestars = Icon = etc.?”
On mesh specifically, I’d read about the melting and that’s why I always, no matter how much I’m tempted by the heat, wear jeans underneath. Also usually wear a long sleeve shirt under my mesh jacket, though as the temperatures rise, I sometimes wear just a t-shirt.