"One could also move away from the private keys, and simply allow the SP holder to add the usernames of the parties he would like to have representing his voting power to a specific list in the wallet, with limits of percentage of total SP each representative could wield."

I like this more than the private keys idea.

I would also propose that maybe the voting payout should be shared between all posts across the UI. That way, whoever does have the most votes within the allotted time gets the biggest pay out. I don't like seeing a post with a majority of votes getting less than a post that's got 10. It's a huge kick-in-the-guts to us who want to impose a form of equality here. We could do this by giving a time restriction on a Curator's vote rather than an Authors's post.