I shoot with a D3x, and I own all 3 of Nikons PC-E lenses, The 85mm is the top performer, much better then the 24 or 45mm.
I found when I use to shoot with the D700 all 3 lens performed very well, but when I moved up to the D3x, 24mp starting showing the short comings of the 24 and 45mm lenses. I believe it's the same with canon. Same story. The 90mm is stellar but the 45mm on the 1Ds MKIII and 5d MKII is not as good as the zeiss 50mm macro, take a lppk at diglloyd.com he has done extensive testing.
I just rented the 35mm and 50mm zeiss and will be doing some tests this week.
Yes I love having the shift option for framing purposes, works great, but.... on my D3x the files are not what I call "crackling" when I use the 45mm PC-E lens.
What I have found is purchasing lenses for 24mo FF DSLR, you have to have the absolute best lens in front or your wasting your money on the higher MP.
I am also pretty sure it's the same way with canon, and to be honest it will be very interesting to see when the IDS MKIV is releases with even a higher mp what lenses will actually be up to the call for this body. I can't imagine any of the current zooms will fair to well. Will be interesting for sure.
Steven