I've been spinning my 04 FJR on the centerstand since I bought it new and also my 83 Venture since new in 83. No problems on either one. The Venture is easier to spin because it is more evenly balanced.
I have been rebuilding a wrecked 05 this winter and have used both a square carpet sample under the center stand as well as a carpet remnant that runs the full length of the bike. The bike turns a little easier on the carpet sample than the remnant, but I find both to have worked very well to slide and turn the bike well on its center stand.
Not enough room for a wheelie & spin it on the back wheel? :yahoo:
Seriously....what about a thin piece of polished wood, about 2' square, maybe 1/4 ply varnished, then a piece of carpet on top of that (upside down). Put the stand down on that and it should spin easily.