That actually is on the todo list... Supporting most of the built-in events, rather than just disks_mounted Pretty painless for me to add to it.
Of course, that brings up some caveats for the users as it's a pain to understand the subtleties between some of them. Maybe I'd just have certain of the events listed as "recommended".
Having something run 5 minutes after array start I just don't foresee happening anytime soon. The sleep is the way to do it. Of course it does appear that there's an issue with scripts running at array start hanging the system, so I've got to figure that out over the next few days....