Depends on the software.

For example, Adobe LightRoom 4 Beta has a selective moire reducing brush.

Some moire can't always be 100% eliminated in post but alot can.

Alot of the decision on whether to go with the E will depend on what you are typically shooting and how much time you want to spend in post potentially cleaning it up. The primarily landscape photographer isn't going to care much and will do the E, but the photographer doing 100s to 1000s of frames a day or architecture or of products with alot of potentially moire inducing patterns is going to care alot and probably not want to have to spend the time in post.

Luis Gonzalez
Everlasting Photography, Inc.