I've done small amounts of FMQ on both of my 431Gs. It's essentially the German cousin of the 401, but with an open arm and the ability to chainstitch. They do fine. I used the darning foot that came with the machines, it's a 161596, almost all metal, but the very end of it. It squeaks though, and I douse it with Tri-flow when it does it. This foot from Alphasew may do the trick - P60417, though I don't love it, it seems like there's a "blind spot" from the plastic, which is slightly absurd, considering that it's clear plastic.
I've also found that these machines seem to like a faster stitch speed for some reason, but not too fast, or you create eyelashing in corners.
Many people choose not to drop the dogs to FMQ, including Leah Day, so don't let that hold you back.
http://www.daystyledesigns.com/doiha...myfeeddogs.htm
That said, I do find the 301 much easier to FMQ on. It "just works" where as it feels like I'm "concentrating" on the 431 to get a good result.