Lol, I'm sorry Catlemur, but I see no way this could bring about racism, and it would only bring about discrimination if there were enough people without consciouses. Anyways, my view is that we were fine as a community without Karma, and from what I see, the possibility for failure is low with this Karma system.
Personally I don't really care though either way.
Some (more sensitive) people may care though, so if it is possible, you could give people the choice of showing Karma or not. If you are unable to give people this choice, then I'd say to turn it off. I'd prefer people not being 'hurt' by a dumb little number.