I'm not sure that last one is really a drawback. It amounts to encouraging more active participation from people with good judgement. That would be a good thing.

I think I was unclear in my earlier comment: when I wrote "I suppose what you'd want is ..." I didn't actually mean I thought that was what you were proposing. I was ruminating on what happens if one takes seriously the idea of estimating how much evidence a given vote from someone with a given historical voting pattern provides.

I agree that just restricting the amount of voting each user can do is a simpler way to achieve something along similar lines.