Yup, Canon`s mic holders are pain in the a$$ but you can cut some small and soft rubber tubing to fill the caps between the holder`s holders ad you`ve got a kind of a schock mount. I clued those little soft-rubber tubes with hot silicone so I have standard 19-21mm dimetre mic holder.
Yeah size is wierd thats for sure. Easily fixed if you must use it. I use a spare piece of foam cut from my Pelican case. I just cut one that rings the mic about half circumference and hold it on top, push down and tighten screw.
the h1 is the same way, they made the mic holder to be sized for the canon shotgun that comes with the h1. i have to do the same thing whenever i use a shotgun on the h1. def a pain. what were you thinking canon?