quick thread hijack, just curious how crucial is the IS on this lens? Is it worth the nearly $1000 price increase over the non-IS?
Depends on what you shoot. If it's always action, then you may not need the IS since you'll always have your shutter speed up there. I use my lens for portraits, as well as other things, and for me, I appreciate having the IS.
To the originial question, I paid full retail when it came out as well and I think that it was worth every single penny.