Dunno about steel spur gears. I'd check the mesh and hope it was just a stray rock that got stuck between the chassis and the gear that killed the spur. That's how I stripped mine, and I think that was the only time.
I tried the floating rear mount. Now I have to figure out where to go with the suspension. Instead of rolling around the corners, the rear seems to either drag or skip around the corners. Also, I'm getting a rather nasty spin coming out the corner with some gas. Really disconcerting. Softer springs in the back? (I think I'm on either the Ofna purple or copper, can't remember at work)
Even with all that (tricky rear end, fried glow plugs) I managed to come in 2nd this sunday!