Is there anything about the nature of inotify's inotifywait that would result in unpredictable behavior (or predictable problems) when running two or more scripts that each uses inotifywait to watch the same file or set of files?
Or is it safe/ok, technically, to have multiple scripts using inotifywait on the same files?
Yes, it is safe. inotify is a Linux kernel API which allows concurency.