Well I researched this particular derailleur and I found multiple reports calling it an extremely unreliable component. Some took this to the extreme as labeling it a contributing factor to Suntour's demise.
Well as someone who didn't want this derailleur to do to my morning commute what it is accused of doing to Suntour, I borrowed the rear derailleur from my old mountain bike (a Shimano Acera).
It seems to shift like a champ with my friction shifters. There is one problem... The derailleur does appear to rub against the metal disk behind the freewheel when I shift to the largest rear gear.
Is there a way to remove this without having to rebuild the wheel?