I don't believe the geo location of the ip address will matter much anymore (we have a high-ranking site with an ip address in Germany). I think the larger issues may be tied in with how fast the server is and the frequency of change of the ip address tied to the site (so if the ip address changes a ton). Even if it is a seo factor today, I would not expect it to be weighed heavily.
Would be interested in hearing different opinions/experience with this though.