Personally, I prefer the one-way in almost every circumstance (even foam tires on carpet) unless there's almost no rear traction. On asphalt, I use the one way exclusively, but might try a diff to see if there isn't an improvement (hard braking can be tricky w/ the one way, but if your car isn't tweaked it's not so bad.
) As for a spool, you'll definitely see more wear in your CVDs and front tires, and turn in will be diminshed. I used to drive a Serpent Impulse with a spool, and it was very easy to drive; the problem I had was having to slow down too much to enter a turn.