I looked at a few youtube videos for comparison and IMO the difference in negligible.
However, i see two flaws that would annoy me with the replay:
1. No protective case. So if your mount doesnt hold correctly and the camera falls, its taking the brunt of the force. As opposed to the GoPro's plastic & padded case.
2. Doesnt appear to have the option to add an LCD viewfinder. Sure its extra on the Gopro, but it makes setup 10x easier. You're not guesstimating the angle, you can actually view how the shot will look beforehand.
Though maybe i'm biased as i own a GoPro hd:
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