If the clutch is holding the engine at peak torque on the starts, unless there is a significant difference in the amount of heat produced, (heat being a power loss.) both clutches are transferring pretty much the same amount of torque to the axle. If there's any difference in power transferred, it would be in the higher rpm range where one clutch might be slipping more than the other. The amount they slip is very small, but there is some slip. Pete Muller once had an article on his website that showed why light shoes with light springs slipped a little more, on the top end, than heavy shoes with heavy springs even though both slipped the same amount on the bottom end. When the Horstman disk clutch 1st came out there was a definite difference in top-in between the centrifugal clutches of the day and the Horstman disk. The disk slipped much less on the top-end.
