After a couple of rides on rented bikes, I have decided to upgrade to electric. I am currently running D/A 7900 on my Seven bike. I have already replaced the 7900 crankset with a Clavicula. I am running EE brakes, which I also plan to keep. Hence, I will only be replacing the shifters, derailleurs and cassette. I could go either Campy or Shimano at this point without mixing components. I have not seen any direct comparisons between 9070 and EPS. The upgrade prices are similar. I would like to hear informed opinions about which electric system works better and which is lighter. If possible, I will use an internal battery.
I would go with Di2 (which I have) for two main reasons:
1) The Campy design to put the brains of the system in the battery is a bad move. Batteries wear out and I can't help but think that in ~5 years if you need a new battery it will be a burdensome replacement cost on Campy vs Shimano. To their credit, they are getting around to doing a batter that fits in the seatpost, so they have closed that gap. I still don't agree with their engineering decision though.
2) I have a Seven that is drilled for Di2, but yours probably isn't so you will need to run some cabling around the outside. Shimano has a new wireless piece for the RD that eliminates some of the external wiring. This speaks to a better future for fewer external wires on Di2.
I have only ridden the Shimano approach. I'm sure EPS is lovely in its own right but I sense that Shimano is more refined and they have nailed it better.