TechDirt has an article explaining why full feeds lead to more page views on your site than partial feeds.
From the article:
Full text feeds makes the reading process much easier. It means it's that much more likely that someone reads the full piece and actually understands what's being said - which makes it much, much, much more likely that they'll then forward it on to someone else, or blog about it themselves, or post it to Digg or Reddit or Slashdot or Fark or any other such thing - and that generates more traffic and interest and page views from new readers, who we hope subscribe to the RSS feed and become regular readers as well. The whole idea is that by making it easier and easier for anyone to read and fully grasp our content, the more likely they are to spread it via word of mouth, and that tends to lead to much greater adoption than by limiting what we give to our readers and begging them to come to our site if they want to read more than a sentence or two.
I have long had full feeds on this site and have written numerous times about the merit of full feeds.
Further, I don't subscribe to any sites which only publish partial feeds - it is a waste of my time having to click through to read the full article on the original site.
You can be sure I am not the only one who thinks this way!