I have to admit to feeling a warm glow of satisfaction reading another thread about why my Di2 is playing up again.
Now this is a bit of topic, I have nothing against Di2 and if you want one why not, but I have considered it on several occasions and can't see any benefits for my use, I have spent a lifetime repairing mechanical things and a well maintained normal gear system just works, with no battery, remembering to charge etc involved, Di2 you press a button it changes gear, I move a lever it changes gear.
Another off topic bit, car electrical fuel injection is obviously universal nowadays, but the mechanical injection system on my lads early 1980s Sirocco was a match for any modern system, and a interesting thing to work on.