Having made thousands of drum scans over the years, I'd have to say that only a very small minority of scans can actually benefit from 8000 dpi resolution. I've done quite a few comparisons scanning the same film at both resolutions (and yes, there's a bug in Trident that defaults to 6 microns at 8000, so you have to set it manually for the highest rez) and only the images that are shot on the sharpest film with the sharpest lenses at the optimum apertures will show any real benefit. Images on Velvia 50, T-Max100, Technical Pan and Kodachrome 25 are all good candidates. All too often, images are suffering from camera movement, missed focus or diffraction, all limiting what is available in any scan. Very few people actually need scans from 2-1/4, let alone 4x5 higher than 4000 ppi, and it's highly doubtful that any 8x10 lens can resolve that kind of detail on film. Super large file sizes are a waste for most people most of the time and should only be made when the output requires it and the image supports it. Most clients do not want a two hour download from YouSendit.
