Over the past week I have tried all the image sharpening programs that I could find trials for, including Ninja Noise, Vuescan, Auto Eye, Digital Gem and some others that I quickly tossed into the recycle bin after trying them. NI was FAR better than anyone the other programs I considered. I purchased the Pro version.
On some of the programs I tried, I could barely see a difference in the BEFORE and AFTER image. These programs ranged in the $29 - $199 range.
After reading the reviews, I was most interested in Vuescan, but the demo proved otherwise. On every scan (before and after tweaking), color shifts were very apparent and unacceptable (to me).
Neat Image had, BY FAR, the best image output and moderately easy user interface.
This is truly a remarkable product.
The slow renders are not a concern if you get a version that has the unlimited batch feature.
THANKS FOR THE PRODUCT!