You are totally wrong about the delay, sorry.
Shift move in mechanical is much longer than electric systems shift move (EPS). When you make shift (or push*) move in mechanical system (*Campagnolo) EPS shift is already happened. Trust me, I have both systems on my bikes. Same thing also with Di2 > the mechanical shift move is so slow (long) when compared to Di2.
On both systems (EPS and Di2) front shifter shifting speed is much faster than mechanical. Still all the highend ( Super Record, Record and D-A) mechanical groups are good, but faster than electric ones? No way. Wake up and take the real test ride, before manifest...
I have ridden both (Campy EPS and mechanical, current 11spd). Unbiased. Wide awake. What I trust is that you believe it is faster. That's ok. But I know what I felt, and how it worked for me. And to me, I feel I can shift mechanical faster than it takes for EPS to do the same thing. Plus, mechanical just feels better to me and that is no small thing. Especially when shifting multiple gears. I know where I'm going to land with mechanical. I can throw things around any which way. It works. And if something does go wrong I can recitfy it. Turst me on this, if I wanted EPS, I would have it right now. I don't like the way it sounds, I don't like the way it feels. I prefer mechanical. It comes down to personal preference I guess. But I don't think anyone is going to lose any races because they don't have electric shifting, be it EPS or Di2.