The point of the Infinity Extreme is the "one tool" aspect. You end up with some extension as a result of it, but that's not really the goal, just a side-effect.
I have an extension that is similar to the CMT, but that was for a specific depth situation. It still takes 2 wrenches, so no advantage other than the length. So far it has only been a one-time-use thing, but it's in the arsenal, ready.
The Muscle Chuck seems like a similar bit holding method, with a different mounting to the router.
The Infinity being more universal, and the other potentially more rigid, but limited to certain models.