Shoot in color... convert in Editing Software
Shoot in color... convert in Editing Software
There is far more control over things like grain and tonality for black and white conversions by converting digital color images in software.
Sorry, can't tell you how the Canon 5D shoots in black and white because I don't use it that way. I haven't shot any digital camera in B/W mode since moving from Point and Shoots.
As a professional told me, shooting digital in black and white makes absolutely no sense. Why bring home an image that is compromised by the camera. There is so much you can to converting to and editing B/W with all the color information left in the file.
Others may be able to answer your question, but my personal opinion is "don't use the camera to create monochrome images". You won't have nearly as much latitude in Post Processing.
Considering your choice of the 5D, I personally think at the prices a nice 5D body sells for ($1000-1200), it is one of the best values in entry to Full Frame digital. The reviews have been incredible for that camera since it came out, and many are only now replacing them since the MkII 5D came out. I wouldn't be surprised to find the MkII not as ultimately desirable, except for those who truly need the increased resolution, for printing larger prints. I do not regret for a moment ending up with the Canon 5D MkI.
It would be a shame to see you pass on the 5D because of the OOC B/W, since I think that's an extremely short sighted approach to digital B/W. (again, personal observation)