I've been using an Ion Speed Pro since July 2016. Similar shape to the Contour Roam cameras -- cylindrical, versatile low profile mounting options. But it's quirky with pros and cons.
Pros:
Inexpensive
Runs 90 minutes or longer.
Weatherproof without special housing (but rear cap must be in place).
Runs for hours off an external USB battery (without weatherproof cap).
Easy to operate
Decent flare-resistant ultra-wide lens and good daylight resolution.
Ruggedly made and generally reliable.
Cons:
Customer support mediocre
170 degree ultra wide angle lens is really too wide for traffic documentation. It's better suited to close up action cam videos.
Mediocre nighttime resolution -- very noisy, poor dynamic range, may not record license plates.
The only really annoying glitch has been with freshly formatted media cards. For some reason it takes several uses, recording and erasing files, before it runs continuously without stopping prematurely. With a freshly formatted Sandisk card it tends to run for only 30-60 seconds, then stop unexpectedly. When restarted it should run about 40 minutes continuously per file, then automatically switch to the next file (seamlessly) and record continuously until the battery is exhausted or media card is filled. Ion recommended formatting only once, then deleting files when finished rather than reformatting. I've tried both and they seem to be correct. As long as I delete files when finished without reformatting the card I experience fewer glitches. But I still need to check the camera often to be sure it's recording.
While I'm satisfied overall with the Ion Speed Pro I may try a Contour Roam next since they're comparably priced, and I like the cylindrical form and weather resistance without special housing.
The Moebius dash cams may be the best values, although they're not weather resistant -- they're intended for vehicle dashboards. And they need external power supplies. But housings are available, as are inexpensive USB port lithium ion batteries.
However there are so many video cams for $100 or less suitable for dashboards, action, etc., with new entries every month. The Techmoan channel on YouTube is a good place to start.