I think it would be good if you could adjust the green percentage when greening up.
So for example, if you back Player A and then lay them at a lower price using identical stakes you are left with 100% potential profit on Player A. Greening up obviously allows you to shift 50% of the profit over to Player B, but what if you decide you want to shift more of the profit to Player B, say 75% or even 100%.
I'm envisaging some sort of slider above the 'Green' button that allows you to shift your profit/loss one way or another depending on what outcome you feel is most likely.
Not quite sure how this would work on larger markets with more possible outcomes, maybe manual percentage boxes next to each selection or something similar.
Let me know your thoughts!