If the magic lens fairy would only leave another $6K under my pillow I'd love to trade my 500 for one of these things. Barring that my hope is that all the cool rich amateurs will decide that the 600II is the new "it" lens and dump their old, heavy, blah 800L's. If I can't trade up to a 600II, finding an 800 for under $9K would console me well enough.
A boy can dream can't he?
BTW. It seems to me that a large portion of the weight savings on the new II series superteles is the elimination of the unpowered protective front glass. This front element could be easily (and relatively cheaply) replaced on the older lenses if damaged. The front element on the new lenses is a high dollar powered optic. I suspect the days of a $500 front element replacement are over.