You're right, Andy. I've had a closer look, and yes, there are benefits, but increasingly marginal ones.
Here's a few quotes that I've picked up, they can say these things much better than I can. Hope it's alright to post them here:
<Actually, I'd personally recommend people use the second version - absolute URLs - certainly on major entry pages (such as the main domain index page).
That will help stop PR being split between important pages. At least if people use the
http://www. prefix - or not - will become irrelevant if absolute URLs are used, as the visitors - and PR - will be directed to specific links. However, if your site is accessed using the
http://www. and without the prefix, then your entire site could suffer with split PR.
Main thing, I think, is to not link to your home page with a relative <a href="index.html"> because you then may be splitting PR between
http://yoursite.com/ and
http://yoursite.com/index.html which search engines regard as different things/places entirely. >
<Without absolute urls there may end up being some confusion between
http://www.yoursite.com/somepage.html and
http://yoursite.com/somepage.html because your'e not making it clear which one it is.
Google has been pretty buggy on this lately and may be best to avoid the possibility of problems from the start.>
<I've been using absolute urls for a couple of years now and haven't seen any negative consequences. I am pretty sure most of the major SE spiders have the ability to determine whether the link is from the same site or an outside site. They just have to do a little regular expression work -- parsing urls and comparing strings. I started to do this because I was finding duplicate pages showing up in the SEs, ones with the www and pages without. Now I do it because I do not want to leave anything to chance, sometimes bots are very stupid. >
<if you have absolute links, you know that it's much harder for a spider to mess up. If you have relative links, there's always a chance that you didn't write it correctly, or the spider won't decipher it correctly.>