I find this a humorous comment as I've used Ultegra since it was the 600 series, had STI Ultegra in it's 8-9-10 & 11 spd. series, plus 5800 and 7000 105 groups on about 15 bikes I've built up from frames.

Di2 - IN MY OPINION, and for the 80?? (can't remember - 8020 ?, 8050 ?) group I installed 2 years ago, shifts quicker, quietly (well except for the front cheep), and more reliably that any of the Ultegra or 105 mechanical groups. All of which were installed correctly and in the beginning, needed no maintenance. Which seems to be what the majority of users on this thread report as well. It's not about maintenance though I would change my comment to just state "better".