Slippers on a 4WD I'd say would mainly be for protecting the drivetrain, the forward traction is plentyful, and I'm not sure you notice a much smoother power output on a 4WD unless you'd put something the likes of a Losi Hydra Drive on there? (After all 4WDs are both driven agressively and built to do so by nature).
So if HB is confident about the strength of their drivetrain and electric motors, plus the capability to keep parts cool (particularly motor), why not?
