You might want go to the SilverFast forum and post a comment concerning the SilverFast preview vs. Photoshop display. Maybe it's another bug that they aren't aware of and one that can easily be fixed it in a new release of SilverFast. I don't use USM in SilverFast (I don't think many photographers do), so I haven't seen the problem.
In a message dated 10/28/2001 12:54:41 PM Pacific Standard Time, firstname.lastname@example.org writes:
I recall, as someone mentioned, that Ian Lyons had pointed up the usefulness
of USM, or perhaps sharpening in general, in Silverfast, even that it is
superior to PS, I think. There is an "Auto Sharpen" filter and the USM
filter has many parameters, even seemingly beyond those in PS.
My problem is that the preview doesn't seem quite accurate, at least not to
what one eventually sees in PS. It does certainly seem to show the view in
actual pixels, but it looks as though it has sharpened a bit more than
anticipated once the image is viewed in PS.