Straight lines

[mattallen37]

Well, you can't have the best of everything.

The NXT motors may be bulky and a bit slow, but they are extremely accurate, with the built in encoders and all.

The PF M-Motors are small and fast (typically a little too fast), but they are very weak, and they don't have built in encoders. To use them, you would probably need to add encoders, which only adds to the size, friction, and complexity.

I would really REALLY try to use the NXT motors for anything that requires accurate driving.