All unusual or specific situations, I guess. There are always exceptions.
Yeah, very true.
I don't see why anyone would mine on Server 2008, unless you actually had some nice cards in a real server that had hardware which truly required that OS.
Well.. matter of taste I guess.
I personally see no reason why s1 would ever use 95/98/me/xp/vista/7/8 ; )
Especially on headless mining rig.