Add 1 more to the 'It was not broken / confusing" so why change it crowd.
IMHO way too many try and attract new users be 'updating' their
image and alienating the existing ones. Go Bud Lite

(Not that I would waste my 1 beer a day limit on a Lite one

)
Calibre is about Books. The 6 book logo (there are 2 thin ones), conveys that. OTOH the proposal has a fan of pages. Nice, but not books.
One thing a long time logo conveys is: "I've been around since your Grand Pa's time. I will be here for your Grand Kids".