I have a new client that was getting pretty good SERPS from a site that was sub-par. The site's structures and links were not done correctly and the on-page optimization used some vintage tricks (that no longer worked). Regardless, this site was 4th in the SERPs for their targeted generic keywords related to their industry, but received no results from the more specific keywords depicting their actual products. I completed gutted the site, cleaned up the code and structure, and properly optimized the site. They already have good backlinks and have a higher PR(4) than the 3 sites listed above them in the SERPS. The changes had an immediate impact on the business and I was almost able to double their recent form-submission contacts from the website (unable to track phone calls). However, I'm pretty stressed waiting for the reindexing to see if we go up or down in the rankings. Over time I know the changes I made will result in more traffic and revenue. However, I am a bit nervous about the immediate impact. It is not the end-all if they go down as they have a pretty aggressive PPC campaign going on as well. However, they do see a significant amount of traffic from organic. Anyone else here restructured a moderately successful site? How did it fare in the short-term? Long-term?
I've gotten sites taken off the index for a day or two and then either put back in the same place or in an improved position. Don't forget to use pingomatic or an indexing tool after about six hours after you put the site back in place.