OK, since I now am in the C level of the league, a few things have now changed...
Once you are in the C level (and higher) of league, the Janryumon interface for automatic sorting of tiles is now nashi, but I believe the option will revert to ari once you fall back into D level league. I believe this had been in effect even prior to the changes of July 3.
Your (highest) score for the last 2 weeks in league play will convert to JRM's currency (not the kaimo one!) - this is the reason that my balance in JRM currency is now not divisible by 50 or 100.
Now I do not know what new perks will come being in C league (B, A or even S for that matter), but I will probably see those once I encounter them.