I see, that's good to hear, since KOreader has a direct integration with Calibre, when I connect it to my server it shows up as a external device in Calibre and I can select multiple books in Calibre and directly send to the Kindle in one click which I find more convenient than navigating a OPDS catalog from within my slow kindle and downloading books one by one, but maybe in the future when I get a better e-reader I will give Kavita a try.