Geert makes a good point and the only reason to shoot monochrome in camera is to save time. You have so many more options when converting from color -- from tonal adjustment to what you want to emphasize most. You can convert from one channel, or from hue/saturation, or several other ways. The only time have used B&W in camera is when shooting IR because all the info is in the red channel anyway, and I seem to get a cleaner shot that way.

Kort Kramer - Kramer Kreations