[aiharkness]

I hadn't thought about it, but my definition of a power user would be slightly different, and wouldn't so much describe the hobbiest or enthusiast who experiements and tweeks, but the person who uses the device a lot, and for a lot of purposes and tasks, sort of like what juwaack says, but more to describe the person who relies on the device for a lot of things and is more efficient, more productive, and more powerful because of it.