I'm looking for a sanity check on my approach before I buy the eComm addon...

I want to charge customers a fee for different access to file downloads. From what I'm reading it looks like the eComm addon would allow me to create products that represent file sets, then when they make the purchase, I can configure the product so it automatically adds the user to a particular user group, where that user group will have read privs for the given file set.

Does that fit the eComm paradigm?

Would I need to code anything to glue all this together?