Matthew: I think the sticking point will not only be the lack of any color except black (thank you Henry Ford)but the barcon handle is shaped with subtle finger indents that make slipping on another rubber difficult, and maybe impossible. I always had the idea that these (vinyl) "covers" were actually molded in place and didn't come off except with a knife...but now I'll have to check mine up close and see for certain. If you can live with the SHIMANO Barcon (no ratcheting feature but with a coil "clock spring") these often DID come with a white-or-off-white rubber cover, and those do slip off, IIRC.
Alan Goldsworthy
SF, CA, USA