I porsted a link to the roller foot 31, I really like that one and am thrilled that someone here is going to give the roller a shot.
I also begged for a picture of the treadle 31, so thank you for that! I think it looks super, and am very anxious to hear that it working well for you. My little 103 industrial is nearly the same machine, only it appears taller and has a "stubby" arm...only about an inch longer than normal (say a 15 or 66)