The 201 was the top of the line model, and cost more than the 15 back in the day, it was supposed to be a little "smoother". I agree with Miriam, it could be a noisy motor too.
You are completely welcome to come visit, just set aside at least an afternoon, Ill give you a walk through of the museum (DH asked when we'll start charging admission. ) Some, not all of them, are shown in my blog if you feel like taking a virtual poke around. I've been slowly updating it, but life sometimes gets in the way.
I suspect you may break your promise to the DH,... this is an addiction, just like fabric collecting. You'll almost definitely break it if you come see me... I'll tell you where all the good machines are on the way home, and possibly send you with one or two from here that aren't being used. I think you'll love the FW. I just finished piecing a quilt top on mine. DH fell asleep to the sound of it a couple nights in a row, said it was relaxing. They do have a different sound to them too than the 15 or the 201.