Calibre could care less on how many devices you use with it AS LONG AS you only connect ONE at a time.

Calibre will offer to convert your content to a format that the device accepts
if the format book does not already have the format. (This can add a whole lot of time if the book is complex. I suggest doing the convert in advance, so it will be ready to transfer) Simple Novels Convert on the fly then transfer with very litte delay.