Foot interchangeability with my MC12000 was a big selling point for me when buying the S7. Everything is interchangeable. I use the Acufeed Flex with the 1/4" foot a lot, and not just in quilting. I get perfectly even edges at the end of a seam when piecing, and it works great when sewing on bindings because I don't have to pin, just keep quilt edges and binding butted up to the flange. I can move the needle position quite a bit while in the Patchwork app if I want a wider seam than 1/4".
It's shown here at about 4:15. https://www.youtube.com/watch?v=30U4rCHmT-s
Jan in MD