What are you doing with your pictures? Do you need sealing? Or 5 fps?
Because otherwise, if you feel the need to upgrade, I think you should rather wait for the 5D Mark II (or whatever it'll be called) or upgrade to the 1 Ds Mark II. But honestly, it sounds as if you don't really need the features of the Mark III (correct me if I'm wrong, though). Probably the 5D Mark II will be more on par with the 40D (sealing) than it is now and it is also reasonable to assume that they will increase the resolution. I think that camera is a much more reasonable (in terms of money) upgrade than what you propose now.
To be honest,
From what I see there in your sig you have some nice glass there! Stick with your 5D and perhaps wait for the 5D MK II or whatever it's gonna be called.
1Ds is just an outrageous price for unless your doing some serious sports stuff etc.
I'd say the next 5D is gonna be a great camera. MP bump and a whole load of new features.
Whatever Canon does, Nikon has them beat with the D3, lol
I would much rather have ISO6.4k-25.6k capability with the same MP resolution (apparently Nikon doesn't currently feel they need to bump the MP as much as Canon has done), just too many instances where DOF or slower speed zooms can benefit from higher ISO (especially when you need to handhold shots).
D3 @ ISO 6400, 12,800, 25,600
http://www.robgalbraith.com/bins/multi_page.asp?cid=7-8745-9153
The 5D replacement/update will be likely be along the lines of the other new updates 40D/1Ds...ie. Nikon stold the thunder with their more impressive offerings. 5D mkII would have lower ISO
🙁, some type of live view (boring), lower res LCD screen, and minor seals as in the 40D are nothing to get excited about when Nikon's are more fully sealed.
Going from a 5D to 1Ds, you get a much larger and heavier dSLR, one could hope the saving grace on a 5D update would be significant weight and size reduction...but there are no rumors of anything like that.
At any rate, we can hope that the 5D update gets announced in January along with all new Mac's, in the 1st part of the month
😀