Through the last few patches, even proposing to test a 720 health sherman in any capacity caused people's heads to start spinning. Putting a health bonus with vet 2 and/or 3 to get the Sherman up to 720 or even 800 health was deemed to be catastrophic to 1v1 balance and therefore not even worth testing or considering.
I always figured the call-in Shermans were good at 720 health, but the stock sherman should get that health at some point. I have found it strange in CoH2 that so few vehicles get any durability increases with vet, especially for USF.
USF
needs a late game meat shield. the rather disastrous attempt with terminator rifle and now the Jackson were done because they lack any.
At this point the sherman is the last one we haven't tried, although it's not quite as simple as just giving them 160 more HP.
and 1v1 strength is just a matter of how strong the faction is early game, and team game being 2v2+.
and nearly every other faction get 800 hp on their adv medium. the t34-85, the comet, and the panther all get 800 hp. The ez8 and the bulldozer should have gotten 800 hp as well.
As for the 75mm sherman, the 800 is a good even number in regarding to shot to kill. I don't see why they should deviate.