@Patricia1066: Err, what?
You'll pretty much always have to see it in person to effectively measure how pleasant you find how a specific device handles eInk refreshes.
Kindles tend to be at the forefront of "Doing It Right", though.
(It's unclear to me if you're talking about the good old black flash, which can be controlled, and is getting far more efficient that on older devices, even when you do enforce it; or more subtle trickery involved in non-flashing REAGL updates, which do magically weird shit if you happen to look at it frame-by-frame, which is meaningless, since you're not reading that way
).