In general the transaction was smouth. I moved all content to the server hosting the .com version and used htaccess on the other server to instruct bots that content had moved. The spiders followed the rules and indexed the content in it's new location. I retained the old domain and simply posted a page saying "all content now resides on out main site" and a link to the .com site. After a few months I removed the htaccess file and still get a few referals from people folowing old links. In general the change was fairly smouth. I would say the best time to try this would be right after a main update. the reason for this is because the deep crawl generaly follows shortly ater a main update. This will ensure that your content will all indexed by the following index.
One more question. What happens to your old listings on the search engines once you submit the new listings (with new domain name)?
Won't the search engines see two pages that are exactly alike but using different domain names, then decide to ban you from their site? Or, do they see you have posted on the old site "this site has moved to "widgetworld.com", etc.?