At a minimum, they'll forgo the site's search in favor of external search engines like Google. Not In our recent search study, the mean query length was 2.0 words. Other studies also show a preponderance of simple searches. Most users cannot use advanced search or Boolean query syntax. Do not offer advanced search from the home page.
Advanced search leads users into trouble, as they invariably use it wrong.
Try advanced search. In general, this is dangerous . Users often overlook the scope, or they think they are in a different site area than the one they are actually searching. However, as websites continue to grow and offer multiple services in a single site, my attitude toward scoped search is changing. I now believe scoping can be sufficiently useful if you offer it in areas of the site that are both clearly delimitated and address specific problems.