Here's an interesting thread from today on roadbikereview.com's forums about why some pro teams use Chorus and Ultegra intstead of D/A and Record.
http://forums.roadbikereview.com/showthread.php?t=93606
BTW, you might have to register for roadbikereview.com to read it.
Live with intention. Walk to the edge. Listen hard. Practice wellness. Play with abandon. Laugh. Choose with no regret. Continue to learn. Appreciate your friends. Do what you love. Live as if this is all there is.
--Mary Anne Radmacher