karma balances often get downvoted less than the vote options get upvoted, so this will tend to over-estimate how many people no longer dissent.

To me, when a karma balance is downvoted less than poll options are upvoted, it means that people think running the poll deserves some karma. This does not overestimate people who have reacted to voting patterns, since that number does not come from the karma balance. If someone (who has NOT reacted to voting patterns) wants to give karma for running the poll, they would upvote the karma balance, not the voting comment

Also, the purpose of the poll is to see whether a relatively high or relatively low amount of people have reacted to the voting patterns this way. Exact numbers are not needed.