Well, I'm for a plus wan, but...
How often does the server restart nowadays? Issues with this could be whenever the server turns off, you WILL lose /fly, it wont be on. Solution: Have a dedicated server for just the /fly data, and do we really need that? Unless I'm being stupid and there's another way of doing this.
Another solution is just toggling /fly whenever a user logs in and is an Ultimate. That's not too difficult, and wont cause too many issues.
Anyway, flying is for noobs.