Seems the easiest solution to that would be to simply have a comparison view. The permissions are setup using some sort of sta.dardized method, yes? Config file, GUI, whatever. Certainly it wouldn’t be hard to simply grab and organize a list of perms from both instances and toss em up side by side. Could even add notes (i.e. if photo storage on Instance A > Instance B notify use “migrating to this instance may cause some larger photos to be removed from your account”).

I’m not a professional programmer (sys admin, so mostly just automation) but there are certainly solutions to this.