Blizzard knows about most of these hacks/exploits before the majority of you guys do, the problem is usually there isn't much they can do unless someone reports you. Until they release a new patch to check for this change, there isn't anything to detect. Its the same way they check for model edits that allow for exploiting, like previously with frost shards and the tunnel for Barron mount runs. At some point they will patch and look for this, but there are multiple ways to make such a change so it would only be a temporary solution.
What you need to be concerned with is people seeing the difference (if any is to be seen) and reporting you for it, GMs can't see combat logs from the past or anything like that but you could end up with a invisible GM watching you where he can actively log your dmg/heals, if casts or what not are happening faster because of this it would be easy to prove in that instance.