I just got back from some dives in Maui where I used my Paralenz camera. I like it, but I'm really a stills photographer, so maybe not the best judge. I've never used a GoPro. After dealing with housings and batteries for my still camera, I wanted an easy video camera. The Paralenz does not use a housing. It's shaped like a flashlight and I just used the mask mount. I've seen GoPro users stick their cameras onto sticks to get closer to the fish. You may be able to stick-mount the Paralenz also.
The Paralenz has a non-removable rechargeable battery. I ran it for 2 dives each day at 1080p 60fps and still had a little charge left. You should be able to do a partial battery charge between dives with a USB battery pack.
An interesting feature is its digital color correction (DCC) that you can turn on or off. It's essentially a depth compensating red filter. Supposedly it increases the red correction the deeper you go. I have linked 2 videos below. One starts around 80ft, the other 20-30 ft. There should be a depth display in the videos. With a GoPro, people use flip in red filters of fixed intensity. I don't know how well those work when significantly changing depths. In my videos, when you see the light from other diver's flashlights, and the display screen of my still camera, they look red due to the DCC. Everything is a little too red/purple at times, but the colors a closer to reality than the washed out blue that I would have gotten without the color correction.
I also found the depth reading to be 1.7 feet off. I probably need to calibrate the depth, but haven't found the setting.
The controls took a little getting used to. With the camera mounted on my mask, I couldn't see the text display. When turning it ON or OFF, the camera will vibrate, but I think the vibration pattern is the same for ON and for OFF, so to avoid turning it OFF during my dive, so I just turned it ON shortly before each dive and just left it ON throughout.
It worked well for me. It's pricey, but so are the newer GoPros.
Links to my videos:
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