I wouldn't even attempt to scan color negs without Digital ICE. Without it you'll be working on your negs for years trying to get rid of the scratches and dust spots. Unfortunately it only works for color (except Kodachrome) and not for B&W.
Example for badly scratched negatives from the 70's:
- Single color image would take me about 15 minutes in Photoshop after scanning with Digital ICE to straighten/crop, remove grain, color correct, apply curves and USM. With Digital ICE there are essentially zero noticeable scratches or dust spots.
- Single B&W image can take two hours just to remove scratches and dust spots. Note that I do use canned air before scanning and the room/scanner is pretty clean.
I don't use DEE, GEM, ROC, curves or USM when scanning as I feel I get a much better result in Photoshop (more control). I do use 4X multi-sampling (above that is a waste of time IMO).