I have a friend who plays on an unofficial WoW server. She showed me some footage she recorded from a guild Naxx raid she went on. I have to admit I was highly impressed with the duplication of the encounter mechanics. It wasn't perfect but it sure was close enough for jazz. Also, while I don't condone the whole enterprise as such, the server software is independently developed, not cracked or pirated. As an act of preemptive preservation, we may be very thankful for it when Blizzard close down the official servers (in a decade or so at this rate).