Played with it a bit this morning with my Kilo 2200BDX. A couple of observations...
As I expected, it does not take the place of the BDX app. Solutions in the rangefinder are unaffected by the AB app. Data goes one way, and range/angle go into the AB app from the rangefinder. Whatever profile you have selected through BDX app remains unaffected by AB app.
Solutions remain limited to 800 yards in the rangefinder, and 875 on the basic version of the app.
Big PITA is that the angle does not automatically populate in the app from the RF. If you range a target, you must hit the little RF icon under the "inclination" field to update the firing solution. Range automatically updates when you range a new target, but angle does not.