I agree that there needs to be some slip in the slipper clutch, but the main benefit to the slipper(the way I understand it) is to protect the gears in the tranny from all the brutal shocks from jumping.
The objective is to get as much power to the drive wheels as possible, while still retaining some control. Too much slipper action can generate alot of heat and contribute to premature gear and bearing failure.
I moved my battery forward to combat push that I couldn't seem to tune out with suspension adjustments, and retain other handling characteristics.
I am running the tub style RC10 GT, and that really made the difference in mine.