I have read several studies and comments by sites and their developers over the years that used to offer ranged-based voting (1-4 stars, 1-5 starts, 1-10 rating, etc.) and they found that most users voted either the minimum or maximum each time they voted because when they did not really like or dislike the content, they simply did not care to vote. This is why most sites have replaced their range voting systems with simple up/down, like/dislike, etc. voting systems. You can always do something like make up votes worth 2 or 3 points for example, and leave down votes as -1 point, but that only helps to mask or partially mitigate the problem, not remove it. It just means that it will take a few more users banded together to mute the target user or users. That said, I'm a big fan of keeping things simple, not to mention familiar, and since most users are familiar with the simple up/down system, that would be where I would start.