realwahl - 1:12 pm on May 9, 2011 (gmt 0)
@Sgt_Kickaxe - when you did it, did you experienced a similar drop in trafic? If so, how long did it took to regain the position?
AFTER redirects are in place include BOTH the new pages AND the old pages in your sitemap. Let Google see the new but ensure they see the old and can learn about the 301's. When the old url's are out of the Google cache you can remove them from your sitemap.
This is what I wanted to do. But a few days after the move (301s), I saw in webmaster tools the notice "When we tested a sample of URLs from your Sitemap, we found that some URLs redirect to other locations. We recommend that your Sitemap contain URLs that point to the final destination (the redirect target) instead of redirecting to another URL". I repeted the test now and I got the same notice. At this point, I see no reason to keep the old sitemap.