I am cleaning up a network of very similar sites and rolling them up into a single site. Of the three main sites two were penalized in the Aug 2011 update by Google for having "doorway" pages (with a -50 penalty). Those sites have passed reconsideration requests and are now penalty free. To better comply with Google's best practices instead of operating several near duplicate sites, we will be operating only a single site going forward.
I have heard that there can be issues with redirecting several domains to a single domain at the same time or over a short period of time. Has anyone experienced negative effects from redirecting too many domains at once? Are there any best practices for the lag time between redirecting each domain being shut down to the one that will be retained?
Thanks in advance for any advice.