To be able to vote once every 10 minutes seems a bit much.
A site I go to uses the karma system, but after much tinkering, testing, they set it so users can give one person karma points, every 24 hours. This also forces folks to really muse over whom they feel best deserves it, rather than risk having runaway karma points.
I suppose with too many, it kind of diminishes the point.
Removing the ability to rate negatively accomplishes, to me, only 50% of the issue/s. While it thwarts those who would "Gang up" on someone, it also does nothing to prevent inflated karma points for another. Either way it's a bit of a hassle.
But I do like the idea, the incentive, the way of showing public appreciation for work well done on these forums.
Nice addition, overall.