Originally Posted by InfoGuy

IMO, using different IPs for SEO is irrelevant these days. Google looks at many factors to identify site ownership. Just to name a few, they can link the sites in your network based on registrar, WHOIS info, Google Analytics, social media accounts, affiliate IDs and nuances in coding style or grammar. Not to mention, they read your GMail and know all the sites you visit with Chrome, Android or your IP address.