Everyone seems to run front spools. I tried one many times. I always seems to break the plastic bone blades. I mean they have to be replaced every time I run.
I called Associated and they recommended a slipper spool. It worked much better for me. The problem is it "loosens" up every run. I got by this problem with some locktite on the nut.
All the others racers use the spool, but I like the slipper spool.
Be sure to use locktite and tighten it real tight. This way it acts like a spool, but will give a little if you hit something.