Threads hacking is against the licensing agreement with Groupee (as modifying your forum can break your forum).
ehr, all php files say:
// Note: If you modify ANY code within your UBB, we at Groupee, Inc
// cannot offer you support -- thus modify at your own peril 
You loose support, but it's not a violation against the licensing agreement. Oh well, would be a shame to use any of our 10 support units

I do agree that a forum that fixes your forum and a forum that breaks your forum are better to have seperate

Oh, yes it is. I'd tell you to read the license again but I can't seem to find it on the website. It used to be on the documentation page.
Anyway... does it mean Groupee is going to yank the license right out from under anyone that modifies their own .threads? Well, obviously the fact that Rick and I post on UBBDev answer that.

The protection is in there so that the right is reserved, but in my time with Groupee rarely used.
Support units are good to have if you need help with your board and can't handle it yourself. If you've added "hacks" to your board it's possible Rick could opt not to fix your board though. Or it could be that your support costs an extra unit or two. It's a case by case thing, really.