On improving fairness (and possibly variance for smaller miners/dust payments) I had talked with Sergio from Rootstock and he had some cool ideas. Considering they are going live soon it might be worth following up. The gist was that P2Pool would merge mine both BTC and RSK, and that the block reward would be trustlessly pegged immediately to RSK where smaller payouts could be accumulated and redeemed for BTC when the given miner decided to cash out. There is a lot to flush out there, but at the time (several months ago) Sergio offered to assist with the development.
Sorry Sergio, but that's not a cool idea. For one, it doesn't actually help the fairness problem at all, which is due to DOA/orphan rates being unequal between miners. SDL's proposal only helps with the minimum viable payout size and transaction fees, which is not a problem that we really have with one block a week.
Besides, there are much simpler ways to fix that problem. P2pool could easily encode a balance for each user into the share structure, and only make payouts for users whose balance (including this block) exceeds some threshold. Alternately, for a stateless system, if a user is owed 0.001 BTC and the minimum payout is 0.0015 BTC, we could pay out 2*.001=0.002 BTC each time a block is mined if (parent_hash % 2) == 0. Replace 2 with n for even smaller amounts owed.