I haven't finished servicing my own 201-2 because one of the huge screws holding the motor to the machine is
stuck. I am nervous of using oil on it because the gear worm and armature is right there and I recall reading never put oil there. i think it is was on the vssm blog tutorial of rewiring a potted motor. Anyway, I do use my MIL 201-2 and I absolutely love it. But what I was going to say, I think the 15-91 is probably one of Singers best machines. I use my 15-91 everyday. I do love it, just a bit louder than the 201-2; kind of like driving a tractor vs a rolls Royce.
And I'm really enjoying my Pfaff 130 too. I would love a 301 one-day as a portable machine.