I see no reason not to remove the “no ranked challenges beyond 9-stone rank difference” rule entirely. It’s almost certainly just a matter of deleting the check. As you say, the tournament and ladder scenarios are already testing the system’s ability to handle it, so the risk should be minimal.
Ranked games with more than 9 stones of handicap, though, these should be forbidden.
I think all this is shaping up to be a pretty good set of improvements to the status quo, if I understand the suggestions:
- Show “?” players ranks as “?” everywhere, so they aren’t discouraged by incorrect notions about their rank falling, or who “should” be their strength peers.
- Allow ranked matches between any rank, so that new players can immediately start playing whoever they think is appropriate. (A form of “self-identifying” strength, I suppose.)
- Some kind of “beginner room” system to show beginners the ropes. Either a new system, or bolted onto the existing groups system or whatever, which would probably be easier to implement.
I like it.