With Unifeed you can create as many feed models you need, and then use each of it to generate one ore more data feeds.
It's fully multisite/multistore compatible and managed via magento actions scheduler for periodic automatic updates.
Unifeed is strongly intregrated with Magento caching system, and it's fully optimized to work in background allowing you to manage feeds with thousands products without slowing down performances of your hosting server and store front-end.

Unifeed can manage many variables and methods from your Magento store and adds a series of custom variables and directives to incredibly extend your control about data to fill feeds with.
Variables are values (object references, arrays, text, urls, etc...) usable to get a particular information from your store or a combinations of values. For example: store name, product attributes, product prices, category names, and many many more.
Directives are functions able to process input data to get a specific result. For example: get a variable depending on some Magento configuration, create custom variables, purge html tags from descriptions, and so on.