With the brushless motor the slightest turn breaks the wheels loose.
Haha, I went right up to 100K in mine just for that reason! It's a bit too heavy though, as I have trouble turning sometimes. I'd say 50-70K would be better.
My tires will rub a bit when I land a jump, but not when I turn.
The 60mm Medusa is longer, and so can produce more torque. The 50/60mm are good for 1/10 scale, or 1/8 buggy. The 70/80mm are good for fast 1/8 buggy, or MT (1/10 or 1/8)