All of the chewed up feet were on older machines. They looked like somebody had run the machine with the presser foot down on the feed dogs for an extended period of time. And they are all steel feet.
That's why I was curious about the aluminum ones.
I have a 1/4" foot with the little spring guide on the side I got a couple months ago. I've used it enough that the plating is wearing off the bottom already. So .......
Joe