If it were my community I would test in isolation first. On the other hand we would get more valueable feedback faster by you enabling for your whole community
. Jokes aside, I do think testing in isolation is probably smart but there is no destructive data migrations here. It can be enabled and disabled safely. No decision you make here will lock you in either direction.
I guess I sorta accidently answered this part! Enabling nesting simply creates a nested_topic record for each topic in the DB and kicks off a job to calculate reply counts down the ancestry tree. Disabling nesting removes that nested_topic record and you’re back to flat, no issue.
Feel free to play with it in this category: