I actually know of one significant advantage that the 5D series has over the 1D series - shutter noise!
I primarily photograph wildlife, and I mainly photograph wildlife that is very wild and will not tolerate human nearness. Birds such as turkeys and ducks are uncommonly wary and sensitive to any disturbance.
I set up temporary blinds in key habitat areas and wait extremely quietly for the quarry to approach from the right direction (regarding light). I very, very slowly shift the camera lens in the direction of the bird. Imagine the loud "clunk" that a 1D or 1Ds makes - it immediately spooks the quarry away!
The 5D also has this problem, but not nearly as pronounced. The shutter is quieter than the 1D shutters, and that allows me a little more time with teh subject in range before it spooks.
Hence, I most often take my 5D out to the blind instead of the 1Ds2. But I do greatly appreciate the build quality of the 1D series, and it is with regret that I am forced to use my 5D. The 3fps is hard to live with . . . but then having the first frame spook the bird is even harder to live with.
Why the heck can't they just make the 1D series with a whisper-quiet shutter?
"Your" and "you're" are different words with completely different meanings - please use the correct one.
"They're", "their", and "there" are different words with completely different meanings - please use the correct one.
"Fare" and "fair" are different words with completely different meanings - please use the correct one. The proper expression is "moot point", NOT "mute point".