Something related to persistence: the Post a redirection topic checkbox from the Move Topic page should be disabled by default. Redirection topics left by members are seldom useful and mods leave them sporadically. Having the choice saved would be a small benefit.
Albeit it's more useful for mods when moving lots of threads (had a userscript long time ago disabling the checkbox to save some mouse travel and clicks  ).

Thanks for putting that on your list! IMO it's an easy way to a sort of faux conversation style PMs by having the ability to show all messages to and from a certain user without needing to search for a keyword (there's always that off chance you might miss a PM because it didn't contain that common character you used to search for  ).