I'm building a lot of frames like this so far this winter. This one is a little different as it has a 44 mm ID head tube, the lighter version. The frame is all Columbus tubing- a mixture of Spirit, Life and Zona. I wanted it to be light but not too light so that it might last the ages.
The Di II shifting makes for a very clean setup- no cables at all. The hydraulic line for the rear brake is inside the down tube and is only visible on the chain stay for the most part.