pageoneresults - 2:47 pm on Jul 19, 2010 (gmt 0)

The old URLs are no longer indexed; would rolling back be too late now? META TAGS did change.

YES! Rolling back is too late. You'll send another set of directives and the first set hasn't been fully recalculated yet.

You need to sit back and relax. The change in URIs has a big impact on SERPs during the initial recalculation period and that will vary depending on scope of site, number of URIs changed, etc.

You also need to make sure there are no crawl errors being reported in GWT or whatever tool you may use to review those.

Expect at least a 2-4 week shuffle while old URIs get replaced by new URIs and do the dance. And, depending on the new URI structure, you could have easily taken a step backwards, it really all depends on what you've done and how you've done it.