Originally Posted by Fiemme
The only major advantage of electronic shifting is the auto trim of the front derailleur when the chain rubs. Other than that mechanical works just as well as electronic (Both Campag & Shimano).
Is the extra price of electronic groups worth it when Auto-trim is the only advantage?
I have both, and in my experience in addition to the trim point:
1. Hot days (it gets over 40degrees celsius here), I find mechanical cables seem to stretch a little - at least that is what I am attributing to shifting going out a little.
2. No such thing as cable stretch, loss of "zing" over time.
3. Once set up, Di2 never needs to be tuned again unless crashed.
Here's my own relative ranking from personal experience:
SRAM Red 1st gen: 7/10
SRAM Red current: 8.5/10
DA Di2 1st gen: 8.5/10
DA Mech (current) 9/10
Di2 Ultegra (current) 9.5/10
Di2 11-speed (current) 10/10
Basically, in my experience, the DA mech and 11-speed Di2 are awesome, but Di2 is a little better.
Can't comment on Campag, it's been a while.