Here is the Losi hub. You can see how it keys right onto where the 2 speed clutch normally does. You can see there is no way for it to slip. I dont feel like you could get quite as good of performance with the single speed as with a 2 speed because you will always either have to sacrafice either some torque on the bottom or some speed on top; or a little of both. However, you may be able to sacrafice some bottom end since once you get moving on the track, you shouldnt have to take off from a dead stop much and so it shouldnt hurt the bottom side too much.

http://www.losipartshouse.com/servle...ub-cln-/Detail