I don't see why not...
Overlapping the CC isn't a problem, just make sure that each slot is on a different control channel. I regularly send messages to slots that are not the current focus, so that's not a problem.
It's a bit odd because there seem to be two different channels associated with a slot - one from the zone assignment and one given as the control channel. I'm still trying to figure out all the implications of that oddity, but different messages go through different channels, so sustain, keyboard notes and a few other things go through the zone assigned channel and other CC go through the control channel. It's a bit annoying actually...
Andreas