Posted 02 December 2011 - 04:21 PM
Keep in mind that even if your rankings tank shortly after the redesign goes live, that doesn't necessarily mean that the redesign caused your rankings to tank. There are always other things going on, and changes you experience may not be related directly to changes you've made. After the redesign is published, keep an eye on the number of pages from your domain in Google's index (use the site: operator) and make sure you're verified in Webmaster Tools so you can track your crawl rate, the average time it takes Googlebot to crawl a page, and any other issues that might pop up, like an increase in 404s, soft 404s, duplicate content issues, etc. It's possible your new design is great but something in the code is causing issues with search engines. That's not a reason to go back to the old design, it's a reason to fix the code on the new design.
Also remember that rankings aren't your real goal. You want to increase sales. If the new design is more user-friendly, it should accomplish that. And if your sales go up but your rankings happen to go down at the same time (whatever the cause may be), are you really going to consider the project a failure and go back to what you had before?