I've done 3000+ damage as a heavy by myself. no medics. no dispenser even. Heavies can take more than one hit from saxton with no overheal. they're fine as is. at best they need a movement buff but thats it.
Soldiers need a limit more than heavy though. too many idiots trying to market garden without having the skills to even properly rocket jump. and worse, dont even try to hurt hale unless is with market gardener, so basically a waste of a slot as these punks take away health packs and ammo from those who actually need it. end up dying without doing any damage because of obsession with market gardening. Personally I'm more of a battalions backup kinda soldier. Do damage and save idiots from a rage using the BB buff.