Have you seen the paper, A Puff of Steem: Security Analysis of Decentralized Content Curation (PDF)? I wrote a Steem post about it a couple weeks ago in A game-theoretic model of Steem's curation algorithm. It suggests that before worrying about distributing rewards, Steem may first need to improve its scoring system in order to rank posts correctly.
To that end, I have been advocating for quite some time to explore how a second price auction could be adapted to improve Steem's post valuation. Coincidentally, a few days before you posted this, I finally wrote a simulator to see how payouts would change under a vote-scoring method that's patterned after a second price auction. I wrote a short description on Steem in, Simulating a Steem curation rewards distribution that is modeled after a 2nd price auction. Gametheory.net says:
The theoretical nicety of second price auctions, first pointed out by William Vickrey, is that bidding one's true value is a dominant strategy
It seems that the primary drawback of that method is that it would encourage people to split their stakes, so it might be especially interesting to see how it interacts with the n2/(n + 1) weighting, which has the opposite effect.