A push test isn't going to tell you anything unless the original images were DR limited to start with. Not everything is DR limited, and it's quite possible to fit a lot of scenes within 8-10 stops of DR. For a push test to have any meaning, you need to be exposing scenes with 11-14 stops of DR. THEN you'll really see how far the sensor can go. Oh...you gotta push RAW as well...pushing a JPEG is basically pointless.