Elayne, I have a Singer Quantum LE. According to the manual I don't even need a darning foot for free motion embroidery or quilting (or darning, for that matter). I've tried it and it works; I like it because I can clearly see where the needle is and where it's going. However, I did buy a darning foot from this site
http://www.sewingshop.com/ and it works well on my machine but I cannot cover the feed dogs when using the foot! I wind up with a big mess (bird's nest?) and it doesn't work. It does work well without covering the feed dogs. Does anyone out there know why that would be? And the foot is not supposed to press down on the quilt sandwich.