1. Implement the win-difference config in all divisions.
In my view this config should be made the gold standard for competitive 6v6 at all skill levels. It eliminates "parking the bus" as a viable strategy (something that is really only a problem in matches in the first place), and makes better use of 5CP's offensive/defensive map design. The main argument against this config is that it's too hard to understand, but it really isn't, and the config announcing when the winlimit changes in chat also helps with that.
2. Change the round timer to 4 minutes or 4 minutes 30 seconds.
We saw that a 3 minute timer was too restrictive even for high level teams, and that a 3 minute timer may have nerfed the attacking team too much by denying time for reasonable sac waves. Both the 3 and 5 minute timers are improvements from 10 minutes. However, 5 minutes is still too slow/does not go far enough. I think RGL should recognize that there is still room for reasonable experimentation with the round timer. I lean towards a 4 minute timer.
3. Implement the pick/ban system for all or most divisions.
I think expanding to allow Advanced teams to do pick/bans was a good move, but it's not like Main or even IM teams are too bad to be able to do pick/bans. Pick/bans increase the potential skill ceiling of every team and increase player participation and teamplay at no cost. If RGL wants to keep NC and AM on a set schedule I think that's fine (but not necessary), but there are basically no downsides to allowing teams in lower divisions to do pick/bans in the same way as Adv/Inv. (I also think pick/bans should be done minutes prior to map start, but that's more fringe on my part and more debatable.)
4. Only include new maps that are in active development.
Whenever considering whether to add a new map to the pool, the first question RGL should ask is whether the mapmaker is prepared and willing to change their map (even to a large degree) in response to being tested in the pool. Reckoner is the biggest example of why this rule should be implemented; any valid feedback about the map (the cap point under mid slowing the game down too much, the lower entrance into lobby that shouldn't exist, etc.) didn't matter because the mapmaker quit the game. It's not that most people mind playing new maps -- if suggestion 3 is implemented they can just ban them -- but that people don't enjoy playing new maps that never get updated or never have glaring issues fixed.