Agree with Pomtroll, I have pretty small hands but my thumb comfortably reaches almost the middle of the screen so it shouldn't really be an issue? The tap zones on the Kindle means it's only a fairly narrow band on the left of the screen that turns the page back. Obviously you have to take a little more care, but then you have to take a little care to swipe the right way with the Sony (maybe it's just me that keeps doing it the wrong way
What my point was, it is *possible* to turn the pages using only the left hand. But it's much harder than with the right hand.
It's even harder to turn back a page if you are right handed