Twilkes
Guru
OP came, posted (Mon evening), looked and answered "11sp" Tuesday and gave @Jowwey a 'like', and has not been seen since. As Ian says: probably doesn't care: he was just throwing the question out there.
For interest, how much do you think it would cost @jowwy , going from mechanical 105 rim brakes to Di2 (Ultegra)? Would give us a quantative foundation for whether it was 'worth' adorning a bike costing £1100 retail with Di2?
The two immediate upgrades I'd go for are decent brake pads and decent tyres. Then I'd swap out the calipers.
Can you buy Di2 in a rim brake configuration? Not sure I knew that.