I keep on having this issue and I can't find the "perfect answer":
First of all, I work in ArcGIS 9.3.1. I have 2 layers: roads1950, roads2000. I need to make a layer with roads which were built/changed between 1950-2000. The most perfect thing was to have a "erase-like" tool that would cut out the identical to roads1950 features in roads2000. The problem is that the erase tool only works with polygon layers. I could do a merge and sow out the doubles but it's a (very) long process and it isn't accurate.
Do you know of a tool/method that could help me ?