I do the same. For a few of my books, the publisher imposed a max number of devices. Around 3 or 4 devices. That limitation especially pissed me off. Whenever I get a new phone or tablet, I make sure I always copy over the de-drmed ebook which previously had the device limit. Kind of a pointless gesture, since I'll probably never re-read those specific ebooks, and the publisher will never know I'm spitting in their eye. But it's a good feeling.