We should probably be careful with the term epaper as different manufacturers mean different things when they use it. Some use epaper to mean a non-backlit LCD like the Libre has. Others use it when they really are referring to an e-Ink screen. Still others use it and who knows what they mean by it! So epaper is a confusing term.

BTW, I've got a Sony PRS300. However, I first strip the DRM then use Calibre to modify the Sony purchased ePubs as Sony ePubs are very slow to open and scroll through. I think Sony books have a lot of bloat. Even after modifying the ePubs, it is still slightly slower at page turning and occasionally does take a long time to start if you add a large ebook or several ebooks. Normally though it is about the same speed-wise as my Libre. But I prefer the screen on the Libre to the e-Ink screens, especially in lower lit areas. It seems easier to read, but of course everyone's eyes are different. I hope that one day the Libre will have the functionality of the Sony PRS300 as I really like having TOC capability.