Hello:
I've upgraded my Kobo Aura 2013 to Firmware 4.8.11073.
So far, no library or collection information lost, all ebooks and library data intact
I do note some lag (10 seconds or so) when I switch from current reading to the Home screen; some lag also to reach the Search engine from the Home screen or vice versa. Mind you, I'm writing a few minutes after the upgrade, so that response time might change...
What I do like
a lot are the tiles at the home screen, specially so the tiles for collection or author related to current reading. Also, the library now has
many very useful options and filters to find books according to their reading status, author and so forth.
The Collections (and I have 343 collections

) are
way more fast to reach than on my previous firmware 3.19.5613 installation, so that is an improvement.
Reading progress info, changing pages, reading configuration (font, spacing), table of contents, sleepcover function: all of that is working OK and there are no problems that I could detect.
When I get a better feel of reading and general ereader experience, I might post some more.
So far, so good...
Kind regards,
INCANUS