I am looking into this right now with my CalVin. While the anti-vibration of the floorboards with the raised rubber mats is nice, it moves your feet even higher on a bike with the floorboards way to high to begin with.
I bought a set of the flat floorboard rubbers a few years ago, and had them on the shelf. When I removed the raised rubbers from my CalVin boards, the old rubber would not work as is for two reasons. The new floorboards have raised ribs (stamped in the metal) for stiffness, and present no flat surface to glue the old style rubbers onto. The old style rubbers also slightly overhang in a couple of places (but could be trimmed). I thought I'd look into getting a set of old floorboards and try those. I pulled the floorboards from a friends 76 convert, and they could be made to work with some cutting and grinding. But I decided before I invest in a set of those, I'd revisit the stock CalVin floorboards. I went for a ride on my bike with the raised anti-vibe rubbers removed, and it confirmed my thoughts. That the bike felt much better, I could shift and brake much better, and that my thigh was at a better angle. Given this I then had a flash. I have a can of truck bedliner (brush on, not spray) that I used for the deck on my trailer. It is black, and filled with bits of rubber and provides a tough anti-slip surface. I could paint this onto the floorboards of my CalVin. Right now, I plan to do this, I'm just debating, dipping the whole floorboard or just painting inside the rolled edge (to better emulate the old style rubber pads).