It looks like a serious competitor to the Hema Navigator http://www.hemanavigator.com.au/ And unlike the Hema; it is waterproof, works for 'up to 22 hours' on AA batteries and has worldwide map coverage*.
Oh and a camera.
*The Hema does not advertise worldwide map coverage, but of course you could add any compatible maps to Ozi Explorer, or MemoryMap.
My understanding is that the Hema runs OziExplorer CE with a custom interface. That software works with raster based maps (such as scans of paper maps) and not vector based maps like Garmin. You could use your own raster based mapping on the Montana in the form of BirdsEye products that you subscribe to and Custom Maps that you make yourself however.
Changes made from version 2.60 to 2.70: Fixed issue that could cause the main menu's dashboard to disappear Fixed issue with the photo viewer when there are no photos on the device Fixed issue involving setting the units for proximity alerts Fixed issue with multilingual custom POI files Fixed issue where the geocaching dashboard would occasionally display incorrect terrain and difficulty levels Fixed issue that occasionally occurred when entering the camera page (650 and 650t models) Fixed sporadic camera artifacts (650 and 650t models) Fixed issue involving creating a waypoint with a proximity alarm from a geocache
Own this and have used it for lots of DUal SPort Moto Rides. Amazing! Great screen, way better than any Smart Phone (way easier to use and see at 60mph on a gravel road). Nothing like this. Great routing/mapping/computer planning with the Garmin topo maps for backroads. Will buy City Navigor to check using in the car. The mount is secure and easy to snap in/out. Have used a lot of GPS's but this is remarkable!