Anyone have any experience with the Zero-Max E1 Adjustable Speed Drive or anything like it? It says it uses a series of 4 clutches to reduce the input from anywhere between 0 - 1/4 of its original speed. It's rated for an input of up to 2000 rpm, and it seems to be fairly well made. That's just a general observation though...it seems fairly beefy. I'm not sure what it does to the power/torque of the output though. I don't know if using the clutches as opposed to gears or pulleys means that the s