(An excerpt from www.nikonians.org forum)
"RE: SilverFast vs Vuescan vs Nikon Software"
In my opinion, SilverFast Ai or SE does outperform NikonScan4. The ICC color profiles embedded on the NikonScan are haywired - meaning inaccurate - you'll find reds to be too red and yellows are bland - even though you have matched the profiles from scanner to PS and monitor - you get inaccurate colors - this was on NikonScan4, NikonScan3 was "OK", but after upgrading your scanner's firmware, the ICC profiles do not work properly anymore and you can't use the NikonScan3 too - it has been internally locked and your left to anguish with NikonScan4.
With the SilverFastAi or SE, you get the accurate colors after the prescan! The color correction facilities of the SilverFast is amazing and user friendly - if you have been using NikonScan for 3years, you'll see the difference and you'll never turn back. If you are using LS40, you'll realize too that you don't need the LS50, why? The SilverFast allows you to scan your slides up to 5700dpi! - compared to NikonScan4(2900dpi) and this is on 48bit(Nikon doesn't do this). On 5700dpi resolution, you can see the grain of the film "clearly" with the proverbial smoothness(doesn't mean blurred). It makes you think that probably Nikon is using the same CCD chip for both the LS40 and the higher end models and the only difference is the software(which enables the scanner to scan on the minimum of 2900dpi only - on the SilverFast, this one is bypassed and allows you to use the maximum resolution of 5700dpi! amazing isn't it?)but yes, you would question yourself this after seeing a 5700dpi created out of your LS40 at 150Mb - that is why SilverFast is quite expensive because it is very good or near excellent.
In short, go and try the trial version of the SilverFast Ai or the SE version and don't forget to put your output scan size to 5700dpi - you'll see the difference. Most of the time, I don't adjust any colors on PS anymore - after the scan, I only use PS to save my file, that's it - with NikonScan3 or 4, I spend minutes editing on PS to compensate for its inaccuracies. Do not forget Rule no 1, the lesser processing in PS, the better the quality.
Have fun - you'll notice the quality of Siverfast on my gallery - you can compare my older images(which is from page 3 to 12) is scanned on NikonScan3 or 4, pages 1 and 2 are from SilverFast, you'll see the difference. Most of my uploads are now scanned using SilverFast and you'll see why it's a good buy.
my images: [http://www.nikonians-images.com/galleries/showgallery.php?ppuser=16285&cat=500]