Just playing around, i measured power consumption with two PSU, first one is "high voltage" tablet charger, i runned it with test load and it is stable up to 2.2A, another PSU was some random huawei tablet charger, spec to 2A.
In general, no suprise that most of times when running real life load for chargers, they don't deliver what spec says.
If you are intrested for more data, i can log while printing, or something?
General power consumption figures are also valuable information as a general orientation IMHO. I for one am glad about both those data sources.
edit This Stack Overflow post is also interesting with regards to the Pi's requirements.
I wonder if we could (should?) do anything with the underpower indicator, /sys/class/leds/led1.
I've been thinking about this in the past and started experimenting, but ran into some issues. Which of course I now can't remember the details of 
Semi offtopic, i runned stresstest and rpi-benchmark for both and when 100% cpu load there is only ~one watt difference in power consumption, between pi3 and pi3+.
It would be better if we have Power consumption monitoring of total printer including all the accesories, Pi, camera,.. Etc in octoprint with PZEM 004t power measuring energy module. May be a plugin
