After months of work, we modified all URL's on our site to be 301 redirects to a new URL schema. The new URL schema is more search engine friendly in that it does not have dynamic-looking parameters. What we are seeing after waiting 2-3 weeks is that Google dropped all versions of dynamic-looking URL's in its index, and did NOT replace them with the new version of the URL. We dropped from 120k pages in the index to 87k pages. We also are not coming up for certain keywords that we were always there for, and are seeing 50% less traffic from Google.