ST... how long have you been running V2 and is it stable/safe?
TB-AV. I've had it up for about 4 months. It's been stable. I hesitate to say that it's safe because I'm not an IT security expert, and I don't believe that
anything on the Internet is safe

So far, I have zero down-time and my database seems secure.
Looking back at the original post, I should double-check that the karma system in 2.x does exactly what the OP is asking. (I think I may have slightly misunderstood the question.)
The version that I'm running has a karma system with some configurable parameters, but I want to make certain that it has the exact parameters that the OP asked for.
I'll get back to ya shortly...