In my opion, there could be two gameplay league styles:
1) Players pick the schemes they want to play, from a determined list/pool of accepted schemes. They ban schemes, although, schemes like Team17 wouldn't be banned, because in general even the less skilled players have a real chance of winning. While in Intermediate and Rope Race, these schemes would be banned frequently. Not sure if this is the ideal proposal, but it could be interesting.
2) Scheme-specific leagues for any schemes. Each scheme has its own league, and players ban maps in schemes that the map matter (custom maps). Players ban Special Weapons in Intermediate. In Hysteria I don't know what could be banned, maybe nothing. I think each scheme having its own league would be the ideal proposal, this way there's only complaining about maps, special weapons, and variation scheme files. Everybody play the scheme they want this way, all good players on a scheme would play against the good players of that scheme. A newbie would suffer joining a new scheme league, many addicted pros in each league. Underground schemes could be played on their own league.
Both ideas could exist together, depending on the league mode the players want to play.