Nothing is more annoying, then finding a great site, with solid content, only to syndicate their RSS feed, and see the oh-so-very-annoying "More..." link after 1/2 way through the 2nd sentence.
Here's the thing. The reason I am syndicating your feed, and the reason most others are too, is so I don't have to visit your site, or other's sites, to get your content. I have the feeds that I'm interested in, in my feed reader, so I don't have to visit 100 sites to get the latest news. It comes to me. Why in the world would I want to get just a teaser of the content, and visit your page? Hungry for ad clicks? Want page rank? Looking for site traffic? What?
So, if you publish only descriptions, or summaries in your feeds, chances are, I won't be reading your blog. It's the #1 turnoff for me, and I know, for plenty others. Give me the FULL content. I'm not interested in wasting my time following links going to pages.