Yomu is great, I set up my Calibre Library’s OPDS server, and I can now browse it via Yomu. I’ve synced my ‘up next’ list of books from Calibre to Yomu, and then I’m using the icloud sync to have that set of books available and in sync across Mac, iPhone and iPad.
The reading experience is great; I haven’t tried taking any notes yet though it seems easy.
The only niggle I have is the UI scaling of the library view on Mac, the cover art is too small on my 16" MBP, and I can’t find a way to increase it.