I don't know who had said that they FMQ with their regular 1/4" foot. I have been battling for months trying to FMQ on my 15-91. (which everyone seems to like for FMQ). It sews a beautiful straight stitch but as soon as I dropped the feed dogs and put on any of the various FMQ/darning feet I have, It wouldn't even catch the bobbin thread to bring it to the top let alone sew anything reliably. Since it sews fine with the regular foot. I kept the feed dogs down, put on the straight stitch foot (better viability than my 1/4") and took most of the pressure of the foot and IT WORKS! Now I can practice trying to keep the stitches even and get my rhythm. Now the few slipped stitches are probably user error.
I can finally try to move forward on FMQing.