I would like to see one feature, and that is making the splits variable. I never liked the idea that one who is staked assumes splitting 50/50 is fair, because after all, the person being staked is just free-rolling and has no risk involved. I've seen lots of occurrences when someone will chip in half the buy-in, and the person playing covers the other half, and they split 50/50 so that's why I think it's weird a lot of people are okay covering 100% of the buy-in and splitting by half. So I would like to see in the staking interface a column for the splits, the first number before the slash being what the stakee gets, and the second number being what the staker gets.
Another feature, which might be cool to be implemented far into the future after this staking feature becomes more popular is a bidding system. If a stakee had hot stats and many people wants to stake this player, the stakers put in an offer for how to split the winnings, and the stakee chooses the best one. The system will actually choose by default the staker that gives the biggest cut of course.
These are just ideas. Overall, I think the system is pretty awesome already, and since most people are fine with splitting 50/50, I don't think any of my ideas necessarily need to be implemented, but it's good to have options Well done Zab.