Noise issue can be slightly mitigated by operating it intermittently - fill the tube, switch off the feeder, load up most of the cases in the tube, switch on to re-fill tube. Not consistently with really fast production, but if you're just casually cranking out a hundred or so, most the time can be quiet with just brief bursts of noise. I don't think it's anywhere near "need ear protection," but it is brass cases rattling around a big plastic shell. It's a slight annoyance if you're trying to listen to music or follow dialogue while loading.
I certainly wouldn't want to be without one on my 650. I have no view about how well they work on 550's.