[rogerinnyc]

For what it's worth, installed 3.16 over 3.15 on my H2O (no factory reset), using Mark 4. Patched also to fix footer spacing, font selection, etc. I only use sideloaded Kepubs from Calibre. Result? Significant improvement in responsiveness and page turn speed!! Very glad I updated.

Haven't seen (yet) any of the other problems reported, and I haven't (and don't intend) to try with epubs (I like the Kepub header).

Of course, YMMV.

Edit: Can confirm that the "search in book" bug elsewhere reported is present in 3.16 -- i.e., the search defaults to the prior book opened, although this is easily corrected because it's a drop-down tab and you can just select your current book (but it's an extra step that you need to remember).