I have picked up two or three of the 6.3 as well as the 7.7 models. They seem to be pretty basic cameras, but it does appear that time has been kind to mine. They all work (one needed some shutter exercise to exorcise the sticky shutter syndrome) though all of them would certainly benefit from a good lens cleaning. The bellows, camera condition and chrome all see great.
I have shot Arista EDU 400 film in the 120 versions and the results are relatively low contrast, but I don't think that is a surprise considering they are all pre-war cameras. I think they are probably pretty capable cameras if you learn and work within their limitations. At some point I want to take one out and really spend some time with it to learn the ins and outs of working with one of these old folders, but that will have to wait awhile