I also have to disagree with the statement that "SE spiders disregard relative URLs'. I've been working with
SEO since 1997 and have seen only a couple of sites that used absolute URLs. I have never seen a site disappear from the rankings unless there was some other issue with the site.
Just check the sites that rank in the top ten for any search. It is difficult to find a site using absolute URLs, so it would seem logical that SE read relative URLs just fine.
There are some very valid reasons for using absolute URLs in certain situations, but I have never seen any evidence that spiders have a difficult time with relative URLs in a properly coded site.