Hmmm, this is an interesting discussion of a rather complicated topic, given all the new options out there. That said, I have an Ultegra 6800 CS Di2 with 52-34 and 11-32 and I need more teeth!
I'm looking for the "ultimate" gearing set up that still retains the smooth shifting characteristics of the current Di2 set up. Anyone use the Di2 with say a 36t cassette or a 46-30 cr or similar?
I'm running an Ultegra Di2 11 speed with a 46-30 Sugino crank and an 11-40 Shimano cassette with a Wolf Tooth Road Link on a Seven Evergreen. It all seems to work OK.