Sledge motor weak? Maybe I've been lucky in that regard, as all my sledge motors seem reasonably energetic, even compared to modern Mabuchi FC-130 cans. To qualify that though, all my cars have weak motors.
I have a Europa Vee that, at 10v, can shade contemporary magnetized Scaley sidewinders (Ferrari F430s, DB9Rs, etc). On a straight, the Mabuchi and the sledge are almost a dead heat, but over a lap, the sledge is, unbelievably, faster! To be fair though, the quick lap times of this example are probably more attributable to great handling, rather than the motor, as the Mabuchi can surely must be stronger. In addition, while the modern Scaley sidewinders do have over 100g of magnetic downforce from traction magnets, the powersledge itself does have approximately 20g of magnetic downforce from the motor magnet, so it can't be said that the powersledge car doesn't have some artificial advantage of its own.
On my Matra, the blade is fixed as far aft as possible, but there is still some interference with the bodywork at full deflection. The car runs fine; it's only when the car slides to full opposite lock that the guide occasionally gets hung up, and cannnot return to center.
This is one of those cars that I'd like to find a beat up example of and do a paint job on it; I bet it could be made to look really nice.