I have Di2 on one bike and Etap 11 on the other
No issues with either one so far. But, by far, I do like the one big paddle on each etap shifter way more than the fiddly little ones on Di2. And I think the shift logic / user interface of etap makes as much if not more sense than Di2. Granted you can't shift both front and rear at the exact same time but that just means an extra split second in order to shift both derailleurs one after the other. Also I tried syncro on my Di2 assuming it would revolutionize how I rode my bike. In the end it almost never shifted the gears as efficiently as I could myself in order to match the exact road conditions in the moment.