Been running a dash cam for over a year, and LOVE it.
My personal opinion of the Windshield Witness is that they don't want to be left out of the shopper's eye, so they just down dash cams with GPS since their's does not have it.
GPS is NOT a bad thing. I love saving memorable views when I'm out and about. Having the GPS makes finding something already recorded a breeze. That is because all of the cameras that I've seen that have GPS also impose your location on a map during playback, so finding a single spot on endless hours of video is very easy. Try traveling 3 or 4 hours on an interstate, then playback the video looking for a single event, such as, crossing a state line. The GPS is also needed to capture speed, and since most of us are not in a hurry when in our RVs, speed would not normally be a problem.
The model cam that I use gives you the option of displaying the speed stamped on the video prior to recording, and also saves an independent text file that can be used to show speed. This way, the video file alone can be surrendered, and the speed will not be shown, OR, the video file and matching text file can be surrendered, and wallah, the speed will show on the camera's PC software while the video is being replayed.
Now that I'm finished with my rant about a company that tries to turn people against GPS, here's the real reason for this post. There is a forum that is an extremely good resource when one wants to look at the different dash cams. They are to dash cams what this forum is to RVing. You can view them here:
http://dashcamtalk.com/