I have 2 15-91s that I used exclusively for FMQ. I have 2 because I live at our summer cabin 6 months and then, 6 months at the winter place. I quilt at both places.
I used a $$$$ Viking machine for quilting before I came across the 15s. The 15s are so much better at FMQ than the Viking ever was.
Don't hesitate asking questions about the 15-91. Many of us have them and love them.