Bernhard Kau

This plugin will show the first post with its full text but all the others with the text after the “more” tag

First Post Full Length

This plugin will show the first post with its full text but all the others with the text after the "more" tag

jneuveglise

This plugin will cut your RSS feeds at the “more” tag. It will enable you subscriber to see what you want them to see as on the home of your blog.
It will also add a customizable link at the bottom to the complete article and optionally a fully configurable footer to avoid robots to steal your content.
It will not work if you choose ‘partial’ feeds in the WP configuration.

RSS No More

This plugin will cut your RSS feeds at the 'more' tag or custom [rss-cut] tag and optionally append a footer to each article on your RSS fee …

First Post Full Length vs RSS No More