Originally Posted by sharoney
All I can tell you is what I found when I faced the same decision several months ago.
The difference is, a 201 has a drop-in bobbin, which means the thread has to make a 90 degree turn. The 15-91, which is what I ended up buying, and absolutely LOVE!!! has a vertical bobbin, and thus, no turn for the thread.
Which means that the 15-91 with it's vertical bobbin is fantastic to use for FMQ. The machines with horizontal drop-in bobbins don't do so well because the thread has to turn so much more to make a stitch, making it hard to free motion. Or in the case of my 403, near impossible. Which is why I searched out a 15-91 to use for FMQ (when I learn how to that is :))
Both machines are some of Singer's finest. So you have to ask yourself what you want the machine for? Quilt piecing? FMQ? Or both?