All,
You want to learn about the kings of the industry for this technology? Go to this site:
http://www.nabtescomotioncontrol.com/engineering.php
They absolutely dominate the industrial robotics market. FANUC, ABB, and Motoman all use this gearbox for their main arm joints. I have first hand knowledge that there are at least three of these bad boys (RC-E or RV-C depending upon the need) on each general purpose FANUC robots.
They have cool videos and detailed cross sections of these products.
Why would they do this? They have pretty much all of the patents on this stuff. Many of them are expired, but some of them are still very active.
Anyway, this is the place to go to learn about the best use of Cycloidal gearboxes.
Paul