If B&W Ultra Power Saving is so efficient, why not use as ALWAYS ON SCREEN feature?
Samsung introduced Ultra Power Saving mode, that's besides the usual turn-some-radios-off, sets TouchWiz into a low-demand black and white mode, most likely undervolting the SoC in the process. Sammy promises an extra day of standby in this mode.
So how about using the B&W mode for always-on display notifications?
While it's no e-ink display like the back of the YotaPhone, AMOLED can light up subpixels individually, and lower resolution displaying of non-graphic white content with 90% of all subpixels off and SoC at very low voltage could make sense. Especially if the new pixel arrangement is RGBW (I don't think it is for the S5), cause it would mean that of the 4 million sub-pixels, only a small % of 1 million white pixels would be on... we don't need full screen notifications, just part of the screen...
With some further SW tweak, the phone could recognize when is it in pocket (like Moto X) and when on table, so it should only display stuff then the phone is in horizontal position or when you move it etc. With AMOLED advertised for efficiency, wonder why Sammy haven't attempted something like this yet, maybe add an extra low-power chip to handle this little task (and always-on listening).
Thoughts? Potential? Possibilities?