I prefer shooting in color and converting to B&W later with the Channel Mixer tool in Photoshop, and here's why. When shooting in B&W mode on your camera, you're merely recording the image in grayscale. When converting with Channel Mixer, you're working with three channels. You'll find that your B&W images will have a wider range of tones, and will typically have better contrast. It also allows for better control of the tonal qualities of an image, as some info in one section may have been recorded mostly in red, while a different section may have been recorded mostly in blue. When manipulating the different channels, you can adjust the tonality in ways that would be extremely difficult to do with a straight B&W image.
Doing it this way also allows you to have a color version of the image later. If you suddenly decide you want to see what the color version looks like, VOILA! Go get it printed. Good luck converting a color image to B&W.