The threshold in insurance is in fact "class IV impact resistant" but the actual discount A) is only with some companies and B) not enough to be a deciding factor as far as I'm concerned. I replaced my roof in 2017 and I think it was an extra $800 - $1000 upcharge and I absolutely went that route. Anything that's going to potentially prevent me from having to file a claim next time around is worth it in my eyes. Insurance claims are a pain in the ass so to me the best one is the one that never happens.
Getting a new roof of any kind will usually result in reduced home insurance premiums, going class IV MIGHT make it a bit better.
"Masked Bandit is a gateway drug for frugal spending." - Unknown303