... However, I will note that it is extremely loud (and annoying-sounding) compared to a non-geared 2-roller. I have a garage and a backyard, so that isn't a dealbreaker for me, but it is worth knowing about. ...
I gave this some thought yesterday as I was researching making gears for my mill. (actually, will be a whole new mill, but, gears all the same). I thought I had a gear cutter here that would work, but as it turns out it will not. It's actually for much smaller gears than I want. Correct gear pitch, just not the correct cutter for that gear size and tooth count. It got me to thinking about your statement about how loud that thing is. It's possible they cut those gears with the wrong cutter. Or maybe didn't even use a gear cutter, Idk. Bottom line though, I have made gears with the incorrect cutter before and experienced what you describe. In my case, I was using a plastic gear in tandem with a steel gear, so that the plastic gear was mis-cut didn't really matter since it would eventually wear to fit, so to speak. It was the second replacement of it in 25 years, so I wasn't worried about it failing due to the wrong cutter (and not buying the right one just to make it sound nicer).
There's some math involved in determining the correct gear cutter. It's not rocket science, but it is important. Any gear (involute gears) will require one of 8 cutters depending on what size, shape and tooth count they have. The cutters are numbered 1-8, with 1 for the smallest gear of that pitch and 8 being the largest, or for making a straight gear rack. Using the wrong one for the diameter will result it a gear that makes a lot of noise, at least for a while. In steel, likely it'll make noise forever.
Yesterday I bought a set of 16 diametral pitch gear cutters so I'd have the correct one to make a 46 tooth gear, which is what I need to make my 2.880" pitch diameter gears. (my rollers are just under 3" dia so I need the pitch diameter of the gears to roughly match that in order to have them work with those rollers. )
I found these gears on ebay, but they are 1 tooth too few for my roller diameter. Story of my life.
https://www.ebay.com/itm/35336955 3481