I am just going to use this thread to shoehorn my own suggestion before making an entirely new thread.
The only thing that does not sit right with me about the system is the name itself. "Karma" carries with it this idea of universal balance: do good things get good things, do bad things get bad things - but only half of it applies to the system.
This is a system where you spend someones approval to get rewards, I think a more fitting name for the currency would be something like "Kudos".