I just got the 100 MACRO and it's so light I can't imagine why you'd need one. But if you feel you need to pursue it, you are right to look for a third party instead of the Canon. My understanding is that the plastic adapter in the Canon unit makes it a disaster.
Hi Pinto - The lens is is indeed light and easily handled. I also have an "L" bracket. I thought I was set - but then I was setting up a macro shot and realized that if the camera was at about a 30 degree angle I could improve the composition, and eliminate some undesirable elements.
Ah ha! If I could have rotated the camera on the lens axis... Not necessary, but makes things a whole lot easier.
As for the Canon design - the instructions are useless, and the design really close to elegant but... Do you play golf? If you want to work the ball right to left (a draw) and don't execute perfectly, you end up pushing the ball way to the right - way far away from where you want it. Canon's ring is like that - it is close to be being good, but the way they missed, it is really fouled up, instead.
It will work - that's the best I can say. And WAAAYYY too much money.

