I went back and reconverted one of those images above with the sheep. There isn't a great deal of difference at any viewing ratio between 0 sharpening and -0.7 in SPP.
The real difference comes in the contrast that I applied during PP of the TIFF files. For the first time, I did everything in a batch, and it looks like this resulted in some images that have had too much contrast applied. The sheep image in question for instance looks better with less "aggressive" use of the contrast sliders (I'm using three of them, divided into midtone, highlight, and shadow(.
Thanks for the heads up.