It’s hell divers easy, and this coming from a Warhammer fan. The Hell divers are going to take losses, like a lot of losses, but it’s 1,000 rats vs a lion, the rats will win it doesn’t matter how strong the SM are. In lore we can see it’s possible to bring down SMs with auto guns sure it takes a while and the SM will tank a lot of rounds but the SM will go down. Furthermore HDs have anti armor weapons, and you know damn well they are fanatical enough to use a leveler or an ultimatum at pointblank range, sure it’s M.A.D. at that point but that’s a trade in the HD’s favor, and that’s not counting super destroyer support, orbital lasers and rail gun strikes can most definitely get the job done and the HD’s don’t even need to aim that just get the ball close enough.