Di2 is way too expensive so far. In the next several days, I will add lights, and then within two weeks a cyclometer. The only other item I need to figure out is hydration. I haven't decided between a camelbak type insert in back pack or just use normal water bottles. Problem with water bottles is it wrecks the clean design. The problem with water pack is keeping out mold and plastic taste. I have til spring to figure it out.
I don't think I will ever switch to a rear disk as too expensive and too much trouble. I like the idea of just getting on and riding without messing with wheel changes. The wheels are SRAM S80's. The only downside I have noticed so far is it is a bit noisier. Not bad, but you do notice it.