Ah, interesting, I wasn't aware of that. Perhaps I will go with calibre release then. Thanks for all the input.
Although, it sure would be nice if the calibre releases could be packaged -- this can be done without any reliance on other packages, I believe.
Oh, ha, I didn't even realize you could install it in your home dir and not as root. That answers that question, that's what I'll do.
But it is a bit scary to just run scripts directly downloaded from github...