I'm glad that you are happy (so far) with your Pocket Pro. I love mine!
Most of my books are in Mobi and ePub formats, both of which work well on the Pocket Pro. I've had the fewest problems with the ePub format, the only negative I can think of is that there isn't a 'back' feature after you follow a hyperlink. Mobi works well but occasionally I'll have a mobi book freeze up on me. Holding the 'exit' button down usually fixes the problem.
The user interface does take a little getting use to, mostly because almost every format does things differently (like bookmarking), but it's not too bad once you get use to it.
If you decide to use the mobi format and want to use a custom font, make sure you read the following wiki entry. This information is not in the Pocket Pro's manual or in the online FAQ at the EZreader website. The wiki is for the Hanlin V3 (same as the 6" EZreader), but the information is similar for the Pocket Pro. You have to use the same naming criteria for the font files as shown in this wiki article or you won't see the fonts listed in the mobi reader on the PP. You do not need to have an /index subdirectory in your /fonts directory as stated in the wiki article (that's only required for the 6" model).
https://wiki.mobileread.com/wiki/Hanl..._in_MOBI_files