Printing stills from GoPro footage?

Anyone ever use stills from GoPro videos with success? I'm traveling to Maui soon and picked up a GoPro to use in conjunction with my 6D. The Canon will be used for normal photography but I wanted something to take for snorkeling and documenting the trip. If I happen to get a good video clip of turtles or something underwater I was just wondering if the quality would be good enough to print from a still off of the video. GoPro Hero4 Silver shoots 1080p at 60 frames or 4k at 30 frames. What would you recommend to shoot at?

For stills, 4K would give you nominally more resolution (1080p is about 2Mp).
It might be that the 4K video is more compressed than 1080p so the IQ might suffer (?)

I'd experiment first, but I'll guess that 4K is the way to go.
If your camera supports it, turning on ProTune will give you better images to post-process.

Cheers,

Geoff S.