I also use the Sony leather cover with built in light and like it. I also have a mighty bright, but it uses three AAA batteries making it larger and heavier. The Sony leather cover with built in light only uses one AAA battery and I like they way it folds into the cover for easy storage and portability.
If you know how to strip away the DRM (do a Google search as we cannot talk about it here), then you can use Calibre to convert the ePubs to ePubs with bold text. That also helps in low light situations by adding contrast to the text. If you search a little farther you will learn how to add fonts to the Pocket reader then use Calibre to substitute a better font for the system font. Selecting a heavier font and /or making the text bold both help out a lot, especially in low light situations.