I would very much like these rank-based groups too.
Golf129 wrote:2) I think the expert group should be split into 2 or more levels because I think the level gaps are too wide. e.g. it can be 75,000 - 30,000 then higher than 30,000 or even better 30,000-10,000 and then higher than 10,000. But I know this might make it more difficult to organise so anything you feel comfortable with is fine.
If it's too difficult to organize i could try to help you if you like.