I love giving my customers the entire text Feed, however i in addition have a couple of sites which pull the Feed and connect to us from this. They need me to supply the excerpt/blurbs for that articles as opposed to the full text. Can anybody produce some direction regarding how to achieve this?

It ought to be possible. Wordpress has multiple feed types (see WordPress Feeds) and you will find hooks for every feed type (see Feed Actions API). This indicates that you ought to have the ability to setup one feed type like a partial feed, and the other like a full-text feed. Essentially, you'd you need to be re-writing one of these simple feed types to disregard the setting you indicated around the "Reading through Configurations" admin screen.

I wager this may be done w/ quite a simple plug-in.