Team 418 has used the DeWalt CIM combination for two years now with great success. The transmissions themselves are very reliable IF you build them correctly. You can follow the whitepaper word for word and get a working transmission or you can made specific modifications if you have the experience to understand how everything works. I wouldn't recommend tryint improve the whitepaper if it's your first time working with these, the whitepaper is tried and true.
Another note, if you are using a small #25 chain sprocket with the DeWalt transmissions, make sure your alignment is dead on and your chains are well tensioned. We used a 14 tooth sprocket and on occasion we would throw a chain. Luckily, we managed to fix the problem in the pits, but just a word for the wise.
Also, the McMaster-Carr clamp collars are sufficiently strong to hold any DeWalt-motor assembly. Some of the members on our team were scheptical, so I attached the motors and jerked them around, way more than would happen in competition, and they didn't move at all.
If you want to see how we used them, here are a couple pictures:
http://www.lasarobotics.org/gallery/...T_06_6wk_e0007
http://www.lasarobotics.org/gallery/...T_06_6wk_e0012