The 201 is a great machine for all kinds of sewing, including free-motion quilting and embroidery, but I would much prefer to do FMQ on my 15-91's.
The bobbin holds almost twice as much thread, so you have far fewer bobbin changes. Once you get going with FMQ, even the large class 15 bobbin runs out in 10-15 minutes, so it could be only 6-8 minutes for the class 66 bobbin that the 201 uses.
The bobbin in the 201 is horizontal, which makes the likelihood of skipped stitches higher than the 15, which has a vertical bobbin.
I did my first free-motion quilting on a Touch & Sew 750 years ago (slant needle and horizontal bobbin) before I even knew that it was called free-motion quilting or that the type of baby blanket I was making was called a "wholecloth" quilt.
Years later, I started quilting with another slant-needle machine with a horizontal bobbin - the Singer 401.
I started doing a lot of reading and found that I needed to seek a 15-91 - and a gorgeous one dropped into my lap at a very good price. Even after replacing the wiring and having the motor cleaned and re-wired, it cost only $200 - the same price as my rickety little plastic Brother machine.
I've gotten several 15's since then and a couple of 201's. I absolutely love them all, but when I've got a large quilt to work on, it's always the 15. Smaller quilts, I will do on one of the Kenmores because they are fabulous free-motion quilters, too.