Thank you for creating this @Eridian - it’ll be a big win for both the Reserve and ETH Staking communities 
My 2 gwei on the revenue split for RSR stakers is that 5% is the strictly better option given the compeititive landscape. With 5%, we are on par with Index Coop on a fee basis. This ensures that users do not face a cost disadvantage by going with ETH+ and do not have to decide on this basis. So all things being equal, ETH+ has a clear competitive edge with overcollateralization that makes it tough for anyone to have a strong case for going elsewhere.
Given @tbrent’s great points on what RSR overcollateralization is meant to cover, we are comfortably covered for the anticipated scenarios at 5% revenue to RSR, and so there’s little compromise on this aspect of ETH+'s offering either.
It’s a win-win here 