Well, I have both 50-34 and 52-39-30 bikes.

50-34 is where the Di2 electronic shifters really are nice. Rear shifts are instant, and the fronts are fast and easy, so I'll shift the front even on very small roller hills. I have it set to "shift 3 cogs" on a half second (or longer) "long press". So at the base of a hill, press both bottom paddles with a long press to go to the 34 and to three smaller cogs. Slick. A long press on both top paddles does the opposite at the top of a hill.

This Di2 bike is great on fast-for-me group rides, where I'm often shifting, trying to get a cadence where I can hang on the group. And I'll ride it on a century ride in May that has never ending rollers for most of the ride--I'll be shifting the front all the time there.

I was missing having the 16 cog on the original Ultegra 11-28 cassette. I would often shift back and forth between the 15 and 17, trying to find a good cadence. I'd rather have a 16 and drop the 11.

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My other touring style bike is 11 speed 52-39-30 and either 12-29 or 12-25. I've never had a bike with a 39 chainring before, it's pretty nice. And for reasonably flat rides, the 12-25 is a straight block from 12 to 19, and then 21, 23, 25. I can always find the exact cadence I want with this. (The low 30-25 is about the same as a 34-28.)

The front triple shifter needs to be carefully shifted, slowing my cadence while easing up on the pedals. So I'm more likely to keep it in the "wrong" chainring for a while. But the 39 chainring has a decent range, from about 10 mph up to 22 or so.

This triple setup is great on all-day endurance type rides. My pace is slower and easier, and I can take my time shifting as needed.