That's about the same kind of terrain i run and iv'e lost three 645's. most that run on that type of terrain add weight to help with crawling, preventing it from rolling over and a list of other things for good reason. IMO if you enjoy running these type of RC's (and i know you do) and want to get the most performance from it through DIY things or upgrades. save your self a headache and get a good servo. yes the price is going to be higher but you will be happier when you see that after some wheel/knuckle, beef tube and metal links so and so on your steering won't slow or change in performance as fast as a lower torque servo would.