Thanks, Roger, but I really wish you would have made a bit more effort to put into words what it is about the images from this lens that you like so much.
I used to have a 50/1.5 Opton Sonnar that I used on a Contax IIa, and I felt that sometimes, under the right conditions, it gave pictures with an interesting "look." After thinking about it for a while, I decided to quantify it this way: The lens seemed to flare enough stray light to knock down the contrast of highlights and shadows, but without impairing detail sharpness. The result was a bit like taking pictures on a very slightly foggy day when the sun has just come out -- it's as if the atmosphere has become tangible, but not enough to obscure vision.
I can't tell from your writeup whether the quality you like about the Sonnar-C is something like this, or something else entirely. Looking at the example photos doesn't help because, viewing them online at low resolution, I don't really see anything special about them (other than that they're nice photos, of course.)
Any thoughts?