A slipper-assist clutch’s main purpose in life is to reduce the weight of the lever action. It achieves this through using fewer springs to push the clutch plates together – the fewer the springs the lighter the action required to pull them apart and disengage the clutch.
However, with too little pressure the clutch would start to slip, so a slipper-assist clutch adds angled ramps. During acceleration, these ramps force the clutch together. Then, on deceleration, the opposite happens as the ramps cut the pressure on the clutch plates, allowing them to slip and the clutch to respond like a regular slipper clutch.
A normal slipper clutch’s ramps only come into play on deceleration, so it has more springs and a heavier lever action.