Assuming you've done nothing to reduce the quality of your site, you should not see long-term ranking loss. You will however see movement, both up and down, for a few weeks.
You say you've "created a number of redirect rules". Unless it's a very large, complex site, this should be the case for all pages, and they should return
301 HTTP code.
If you've migrated or retired content before, check for chained redirects: these should be avoided as they will increase page load time, cause unnecessary additional dissipation of PageRank (or equivalents), and may even not be followed at all in some cases.
robots.txt (check specs here) should be present with a reference to a valid XML Sitemap.
Install Google and Bing Webmaster Tools (Yahoo uses Bing's index, so BWT will cover for both) and monitor carefully. Submit your XML Sitemap, and use the various tools at your disposal (manage parameters, geotargeting, what have you) as appropriate to your site.
Don't be immediately alarmed by drops in ranking. Typically things drop (or rise) for a while before settling down.