Di2!

I just finished replacing the Sram Red gruppo with the new electronic shifting Dura Ace Di2.  The component group really makes the bike look great.  It was really quite easy getting everything set up.  The derailler adjustments are a piece of cake.  The rear derailleur can be very fine tuned with up to 25 micro-adjustments per cog.  To make a gear adjustment you simply hold down a small button that changes the derailleur and shifter to adjustment mode.  After that you tap the high and low buttons on the shifter to move the derailleur left or right to center it under the cog.  Shifting is incredibly fast and effortless...especially with the front derailleur.  Shimano includes cable guides that do a great job hiding the cables and protecting them.  Like I said, the bike looks great, and the cable running the length of the underside of the downtube doesn't draw any attention to itself.  The only negative aspect is that the change added a little bit of weight to the bike, but I think the benefits will definitely make it worth a few additional ounces.  I can't wait to ride it this next season.  We'll be taking the bike down with us on our TBS St. George trip where we'll use it as one of our demos.