I have to disagree with you here; vote rigging has been around, since the dawn of democracy, so saying that voting needs to be democratic, doesn't mean you don't have to prevent vote rigging. And as CodeProjects voting system describes it, it to has it's counter measures to handle bad votes, and you also posted that high rep members have more saying than low rep members, so why not say, you can't vote untill "you're 18 year old" AKA "one week old member", that to, would be a good counter measure to handle vote rigging AKA "sign-up and vote, and never hear from that member again". Just saying... ;)
With great code, comes great complexity, so keep it simple stupid...:-\ :-\