I switch back and forth so much, and have done it for so long, it has become second nature. The advantage of shooting black & white is that you make compositions that stand on their own. When you compose a color photograph as though it were black & white, you have a strong composition that color has been incorporate rather than a composition that depends on the color to stand. If a black & white photograph had a composition "that depends on the color to stand", it will tend to fall flat.