Hey! You should know that GoPro has released a newer version of this product: the GoPro Hero 5 Black.
The GoPro HERO4 BLACK is likely the best mountable camera on the market in terms of video quality--though, albeit, the most expensive. Introduced with the GoPro HERO4 SILVER, which is the only GoPro to include a touchscreen, it has the highest video quality yet from the GoPro line, with 4K video at 30fps with a 60 Mb/s bit rate. And if you like to shoot for slo-mos, you'll like the 1080p video that shoots 120 fps that gives you a whole lot more to work with.
While the resolution is high, the Go Pro HERO4 BLACK also includes Protune, which allows for some adjusting to shooting settings, including ISO, white balance, and exposure value. The wide view and shooting modes like time lapse are still included here too. A new mic also helps ensure sound quality is solid too--with twice the dynamic range of the HERO3 cameras.
While the 1/2.3" sensor won't capture the best stills, it will capture at a rate of up to 30 fps to snap the right moment. Don't let the sensor size discourage you though, if you're looking for a mountable camera, there isn't an option with a big sensor--the design just doesn't work for a camera small enough to mount, at least with current technology anyways.
With the included housing, both versions of the GoPro HERO4 are waterproof to 131 feet and designed to withstand drops and bumps as well. Since the GoPro is so popular, there's plenty of accessories that make the GoPro suitable for pretty much any kind of action you want to capture. Since the design hasn't changed much over the years, most older accessories will still be compatible.
While the GoPro should produce excellent videos, there are a few downsides. Battery life is pretty poor, for one thing. You can record for about an hour at full resolution continuously before the battery will quit--less if you leave the wi-fi on. That's a significant difference from the two hours of footage you can get with the GoPro HERO4 SILVER. With the $50 battery pack, you can extend the battery life to about two hours (wi-fi off).
The GoPro HERO4 BLACK is also a bit heavier than the SILVER or the older HERO3's. Mounting it on a surfboard or bike, the difference won't really be noticeable, but it could put a bigger strain on a small drone.
The SILVER edition doesn't offer the high frame rate or 4K video that the black does, but it does offer a built-in touchscreen and better battery life. If you can't decide, there's an accessory screen that can be added to the HERO4 BLACK, it'll just cost you another $80 or so.
The GoPro HERO4 BLACK offers excellent video quality--the trade off is the higher price tag, lower battery life and slightly larger size. If the price tag is too much, take a look at some older GoPro models (HERO3, HERO3+) or a Sony action cam.