You missed it entirely :)
RPM is only part of the equation, surface speed is the important calculation...
You have found this right???
http://straightrazorpalace.com/works...wers-here.html
Everything is there including the calculation for surface speed
I use the HF Buffers with 4 inch wheels I have done a razor or two on them :) I also have 1725 RPM buffers, one thing to really understand is that you control the heat with your actions... The higher speed wheels just need a more delicate touch, remember we are not polishing engine parts here, they are razors everything about them require a delicate touch...