The GH2 has a very good resolution because of the way it down samples of from the sensor and nothing really to do with the pixel count. In actual fact the idea pixel count for the sensor would be the same as the video output resolution as with broadcast video cameras. In short the GH2 has great down sampling that creates sharp pictures and the hack helps to stop that detail being lost in the compression. The nex5n/7 doesn't downsample so well so there is only a limited amount of detail a hack (if ever available) could pull out.
Not sure what the trade off on quality is with 28mbs 60/50fps compared to 24mbs 30/25fps but you certainly don't need twice the bit rate for twice fps as frames aren't encoded separately but in groups.
Denham
