I really like this idea in theory, but my main concern would be people finding opponents for the schemes they want to play.
The players playing the most popular schemes will constantly lead the ladder I fear.
I love the idea of jumping on AG and being able to play League games for Darts, JpBnG, BnG, Big RR, Hoops etc... Those are the schemes I want to play seriously and competitively, but those are pretty much the least popular schemes lol.
I've never enjoyed Singles, because it doesn't represent the things I enjoy playing :/