I got this product almost a year ago in preparation for a long trip to South America. I looked into several options at the time, and this one had a good price point and the capacity that I needed for a trip lasting over two months.
The Royaltek RGM-3800 has space for 650,000 data points when recording standard information (Longitude & Latitude) with capacity decreasing when you add elevation, velocity, etc. Logging in this manner allows for 180 days of recording, 12 hours a day.
The one drawback to this particular device and most others of its size is the limited battery life. On two AAAs the battery lasts between 6-8 hours, so when outdoors or in remote places it limits the usefulness or makes you bring along a ton of extra batteries.
I got around this by using an external battery (Digipower shown) (connected by the USB port) which added a lot more capacity. [On the technical side, two AAAs usually have around 900mAh, and the Digipower device has 3400mAh, giving approximately 4X longer life.] With this battery pack, I got about 3-4 days use out of it between charges.
The log files are stored in the .nmea format, compatible with many geotagging programs, but I've found a useful program for converting .nmea files to KMZ/KML (Google Earth) or GPX if you need to convert to different formats.
Overall a great product I’d recommend for anyone interested in Geotagging their photos on a long or short trip.
this week, and although that wouldn't usually be that newsworthy, I came across some interesting information in my research and "hunt for the best deal".