I think anything that starts to go down the 'intelligent/educated have more power' route is missing the most important elements of democracy. Not only are you cutting out large parts of the population, but these would inevitably have locality/race/income correlations that made the whole thing even uglier. Probably even gender correlations.

Not to mention the problem that people have to choose to take it, and I'm not convinced that wanting to have that power is a good sign that you should. You might have a disproportionate number of ideologues/slight megalomaniacs. Not to mention the 'tragedy of the commons' issue mentioned elsewhere.