I was trying to determine if there was any gain in using SPP 6.0.5 over SPP 5.5.3 to process Merrill X3F files, beside the faster operating speed (on Win 8.1 x64).
With the default sharpness setting of 0.0, SPP 6.0.5 displays a sharper image (may even be too sharp depending on subject matter and taste). Pushing the sharpness slider in SPP 5.5.3 does not quite match it, and strong sharpening often brings out noise and other artifacts.
However, when opening the 16-bit TIFFs from each version of SPP in Photoshop, I noticed that the extra sharpness of the image processed in SPP 6.0.5 was no longer there, while the image from SPP 5.5.3 had the same look as in SPP, which is of course the normal behavior.
The below comparison, with 100% crops from a DP3 Merrill shot, makes it obvious.