Swapped out the XTR Di2 for XT Di2 today. Mainly because I already have XT brakes, wanted a complete group and like the black finish better than the silver XTR parts and I wanted the BlueTooth functionality. Downloaded the iPhone app, got the new BT-DN110 battery and it was pretty much plug and play. Rear derailleur, shifter and new junction box add about 150g in weight. Entire bikes still sub 25lbs (XL frame with tubes) so I'm happy. Thats all.