Folks, I'm thinking of upgrading my ScanWit 2720 to a "real" scanner. I'm quite annoyed that the ScanWit doesn't handle underexposed slides very well. In some cases the colors are WAY! off. I'm thinking of buying a used Nikon LS-2000 or Coolscan IV. The question is just: which one... I probably won't notice the difference between LS-2000's 2700 dpi and Coolscan IV's 2900 dpi. I really don't care if the thing has SCSI or USB interface. Which one is the best buy? Thanks, Tom