[Jazzy Boomers]

Color is intersting but B&W is efficient I think

Yes, but who cares about efficiency in that respect? As long as the usual color displays last for 8+ hours there is no sense in excluding one technology relative to another one. Okay, there may be a point w/r/to weight of the tablet. But typically the instruments we carry the note tablets for are massively heavier than the tablets. 

(If you are concerned about the energy consumption by itself: just drink one cup of coffee less per week, that saves about 40-50 Wh  )

Cheers,
Petra

Nothing to do with the weight, but seems to me B&W reading tablet are better outside in sunny or difficult situation ?