Here are some links to impressions, analyses and images regarding various GPS devices, including comparisons.

Sony HDR-AS30V GPS Data, Sony Software and DashWare analysis - Initial looks as the Sony AS30V Action Camera, the Garmin Edge 510 (for GPS only), and DashWare software to process GPS or other logged data and present it onto a video

Side-by-side Comparison of Sony AS30V and Garmin Edge 510 - Google Earth snapshots of tracks from the devices taken simultaneously and analyzed in a video.

Time delays in Sony AS30V video vs. GPS log - This is a spreadsheet of over 2 dozen video files taken and GPS logs analyzed to answer the question "How long does it take the GPS to achieve 'lock' vs. when the video actually starts?" Turns out, it can take a lot longer than you might imagine (especially given the GPS assist data that is uploaded to the camera.