The dretch bite does have more range than the painsaw, this is because the latter is supposed to be a weapon for taking out structures in a hurry (both enemy and friendly, however that doesn't work too well on servers with autokick on FF). Infact, I think the saw range was reduced several times since 1.0.0. This is because it isn't meant to be 100 credit dretch owning weapon. The fact that a lot of people don't know how to get around killing a painsaw without having a tyrant just makes everyone think it is a super awesome alien slaying weapon or something, it used to be great for killing dragoons and adv dragoons on the right hands, and it probably still is, but with the bigger player numbers on servers you are bound to run into 3-4 aliens at the same time, which is impossible to handle against any decent alien team.