I have just bought a 1Ds Mk3.
I already owned the 17-40, 50mm macro, 90mm TSE and 100mm macro, all of which I had been using with my 5D.
The 17-40mm is seriously compromised by the 21Mp. In short, it is made to look crap.
The 90mm TSE is the best glass I have ever owned, period. Even better than the Schneiders on my Sinar. It is truly astonishing and it gives full expression to the 21Mp. I shot some commercial portraits at the weekend on a job and, without any sharpening whatsoever, zooming in to 100% reveals scary detail!
Canon may be winning the pixel race but Nikon's tradional superiority in glass across the board may mean that their fewer pixels are producing better pictures.
ps. I haven't tried either the 45mm TSE or the 24mm TSE, but I've heaard they're as good as the 90mm. Apparently, in order to cater for the movements that these lenses have, the optics have to be first class. Now why can't they just put those optics in all their other lenses? I need very few lenses (the 50mm macro is my staple) and I would happily pay TSE prices for a 50mm equivalent.