It's not rocket science, they use spring leverage to ease the amount of force to pull the clutch cable. The AMP unit gives the clutch lever a different feel almost like it's snapping the clutch.
It takes a little getting used to but once you have the feel for it, it works very well. My wife has about a thousand miles on hers and reports it works great and her hand is not sore after a full days riding in and out of traffic. The AMP unit mounts neatly under the clutch perch, install easily in less than half and hour. Can be ordered in black, red or chrome. I'm not familiar with the other unit, so no recommendations there.
Fanman