With the latest update from Altium to CS 1.4 I'm quite excited by your headline inclusion:
"Chief among these improvements for CircuitStudio 1.4 is support for natively editing Eagle designs"
New in CircuitStudio | Online Documentation for Altium Products
Please give details of how I Natively edit Eagle designs, i.e. in their original format. E.g. A customer gives me an Eagle design, I edit it, and give it back to them in the same Eagle format they gave it to me in.
At the moment all I can see is the ability to import an Eagle design which converts it to and saves as a native CS file format, which as you can understand is not natively editing an Eagle design.