sorry, but i don't see how this is good if it's just a script and is not implemented directly on the forum. if only you are seeing the randomized users, what's the point?
People will be able to discern who is who based on avatars, merit count, merit history, signature, rank, and probably other things. The point is a random username won't do much if people can still find out who is who IMO. You would need to randomize everything.
or they could just disable the script and see who posted, since it's an end user implementation.