I read this PHD thesis centered around soft focus lenses a while back.
http://hdl.handle.net/10023/505
It was a very interesting walk through many of the technological changes in photography (photography's syntax) and how what we have preferred has changed along the way.
The chase of/debate about the benefits of one photographic characteristic over another has been going on a long, long time.
One of the many interesting concepts in the thesis is that as resolution and sharpness increased the need for retouching and manipulation increased. Soft focus lenses were in large part developed to address the issue of too much sharpness.
In the same way the sharpness of the lenses Stone uses on his Mamiya 7 are simply à la mode rather than a definitive answer.
By the way Stone, before you start drooling over the high resolution of albumen paper understand that you would need to make it from scratch and it would require developing your negatives differently.
Edit (can't resist the next paragraph)