Oh and IIRC 7900 changed it's cable pull on the rear derail as well. Ultegra stayed with the old pull ratio. so...the parts don't really play well between each other either. 7900 is one of Shimano's larger mistakes.

I won't ever forget when 7900 first came out and before it was available to the public IIRC - it ended up on Garmin team bikes for the Tour of Missouri that year. I knew a rider who was on the team and was riding the new group. I was talking to him about different stuff but during the conversation I asked, "so how's the new Dura Ace?" His reply, "OMG it F*^&ing SUCKS! I wish to god they'd let us have our old stuff back!"

...and that stuff was maintained by some of the best mechanics in the business.