I think all 201s originally came with darning foot #121094 in the accessory box, but there are several other versions available since it takes general low shank feet. This darning foot is meant for any free motion work, and there are fantastic examples of darning (super even and flawless) as well as free motion embroidery with it. I'm not sure all low shank feet will work, especially those with spring action can act up. F.ex. the 99 is more limited than the 201 because of the shorter needle and presser foot bar; some jumping feet can push the entire presser bar up when sewing. I think I broke the jumping foot I borrowed from my Elna, when I tried it on the 201 (I still regret doing that, and it's several months ago).
I struggled quite a bit with tension before I managed to free motion quilt on my 201, and I still haven't prefected it. I know it can be done, I rememer an
Australian lady having set up a 201 exclusively for FMQ, doing very nice work. There are a few examples of FMQ with the 201 on the web. I am still working on improving my technique, even movements, steady pace, best tread for the job etc. I am very impressed by the technique and work they manage on treadles. That said, many have model 15 as a favorite for free motion work.