If you strip query parameters, you essentially are telling Google Analytics to strip the keywords from the URL (which really are virtual anyway). The way vBulletin search URLs work, it doesn't give any useful info either way really. But if you were drilling down to individual pages, if you strip keywords, it would look like so:
Without stripping the keywords, those pages would instead look like:
/search.php?searchid=4771051&keywords=searching+for +something
Hopefully that makes more sense...
Either way, drilling down to searchid=1234 is rather useless imo since the searchid is unique only to a single user and a single search.