I just pulled the trigger on the Delta SA180 from Amazon for $90 delivered.

This PDF helped me decide that it was worth the extra money over the HF.
http://www.knifeforums.com/forums/attachment.php?attid/87030/

It also has a four pole motor, meaning that the operating speed is half what the HF sander gets.
The step-pulley transmission is a nice idea, but $70 starts to approach the cost of a real variable frequency drive.
Don't think I'll be doing the pulley mod.

I'll have to figure out what belts to buy tommorow.