Looks more compact etc with only a small difference in video quality?

Any users tried it on MTB pros cons?

Should I just go for Hero4 silver?

thanks

For the money, they are not worth it, the drop in image quality is quite noticeable, the only gain is the smaller size, I would just get the Hero 4 Silver.

The non-replaceable battery could be annoying. If you are filming in high resolution, and using wifi, it probably only lasts 1.5 hours.
For the Hero4 Silver, its easy to carry a couple of spare batteries.