I would imagine that even if they made a Sirrus with Ultegra di2 and disc brakes it would be $5k or more. That seems like a lot of extra money simply to get disk brakes-- and it probably would only be the 8r carbon. The 2013 Limited has 10r carbon. Not the biggest deal, but still a nice upgrade. I am leaning towards the 2013 model. Will use it for a couple of years and if I love the Sirrus will get a new one then.