Good morning,
I sort of have, some days I ride carbon frame/Di2 Ultegra and some days 531 frame/DT shifters.
I am unsure of what you are asking though? :-)
After the novelty wore off I found the carbon/Di2 slighly disappointing, quite possibly it is beyond my needs so I don't reap the real benefits.
Rear changes on Di2 are clearly better than reaching for the DT shifter but in practice add nothing to the enjoyment of the ride.
The front is different matter though in circumstance like coming up to major roundabout; Shifting to the small ring to get a good acceleration and then up change whilst still on the roundabout is a real positive. The rest of the time Di2 is better but again it is "who cares" better, I did see a video with Claris STIs and front changes looked horrible, far worse than a DT shifter.
I think that if your first bike was carbon/Di2 then anything else will be worse, but if your first bike was steel/DT shifters then the improvement may turn out to be "yes, i get that its better" but be disappointed by how little it is better unless you are an elite level rider.
Bye
Ian