The Raynox definitely has some positive qualities. The only drawback I find is that when it's on my macro lens, larger subjects are almost off limits to photograph (unless you want to get a particular body part rather than the whole thing). Often, to get the pic you want, you'd have to remove the Raynox lens (which isn't difficult to do - but still a nuisance). I'm having my wife make me a little 'sock' for it made out of lens cloth so that I can drop it in there without worrying about scratches, etc.
Removing it has a big advantage over removing tubes in the field though no dust issues on the sensor.
That's true - and the very reason I'm making a lens-cloth sack for mine. That way, I can just 'drop it in', slip it in my pocket, and move on to the next shot.