SciFi said:
You aren't supposed to use mass edit, just tag script. It goes wrong too much.
Haven't had any problem with it, mainly since I only use it to deleted a ton of tags, therefor only 2 times of use, tag script you can't delete tag only add them.

Besides, I don't recall him saying we "can't" use it, just to refrain from use it, "unless you know what you're doing, it's very easy to mess things up" I believe what he said to me on MSN, though he might have said something different to you. Either way it worked fine, and it seems to do ok if you just work with one tag at a time.