In order to exclude the participation of alts, the lower three ranks can be neglected in the counting of votes. Or for each item we can calculate the number of sMerits of users who voted / 10.
If you have any suggestions for a voting system, I would love to hear them.
I suggest
instant-runoff voting, and not just because I'm Australian and therefore intimately familiar with it. Also, voting power proportional to sMerit isn't likely to work very well; for one thing, it's impossible to calculate sMerit for merit sources.