As for the SS 4000, go with Vuescan.
> Using both Polarscan and Silverfast, I got terrible results.
You might wish to try version 5.5. Both Insight and SilverFast will produce
excellent scans. Insight is VERY easy to use and whilst SilverFast is
initially quite complex it has the capacity to produce scans from the SS4000
that VueScan users can only dream about (that's not a criticism of VueScan)