No idea if it's some kind of first, but I looked through the forums here and saw no mention of it; we're a 25-man guild but we do 10-mans on Friday nights for a laugh. We managed to kill Council in the hardest combination - small, medium then big:

was great fun, really well designed fight. We did a bunch of other achievements and hard modes but that was the best. And yes my interface is 'unique' (it works for me)