I like the combined two aspects that both Wize and Greg point out.

1. The motor underload can only rev as fast as the load its driving through will allow it.

2. The limited RPM rev range in witch the said motor will operate in with its combined vert stall and rpm shift points.

Both combined would have a effect on any total net effective HP gain of any rotational weight losses.

IMO, no doubt theres a performance gain, but the bigger gain IMO would be the reduced G forces on parts by thousands of pounds. mike