How about "buy mostly from Amazon, strip DRM from those only to store backup copies, occasionally buy epubs from elsewhere when Amazon for some damn reason doesn't have the book, and strip DRM from those to convert for Kindle usage"? Also "Only change metadata when the publisher screwed it up really badly" and "change the occasional cover because the publisher didn't feel it necessary to include a real one"?
In all seriousness, I'm a pretty light Calibre user when compared to most here, 90% of my books come from Amazon because I like the convenience (which means I do very little sideloading), and while I think DRM is evil because it limits your options on which platform/device you choose to read, I can't get too worked up over it thanks to Alf.