2.5kg for the Canon vs. 2.9kg for the Nikon. I doubt you'd find it sufficiently less heavy for it to be considered comfortably hand holdable. Then again, for all I know you may be built like Arnold Schwarzenegger.
Wow.
You may be aware that a new version has been announced by Nikon. VR II but otherwise identical optical formula as the VR I version. Even with VR II (supposedly) providing the ability to shoot up to four stops slower it doesn't match the Canon at (supposedly
) five stops.
I have to say, I consider the price of the Canon to be exorbitant at around 1.5x what I paid for my Nikon. True, the asking price for the VR II version from Nikon is (significantly) higher still, but in time that is almost certain to fall to current prices for the VR I version. As much as I love my Nikon 200mm f/2, I would not have bought it at the price Canon are asking for their own 200mm f/2, outstanding lens though it is without question.
Still, Mike, I well know how addictive purchasing high quality, precision optics can be, and if you do purchase this exotic lens I know you will view it as Gollum does the Ring.
Enjoy it if you do indeed get it.