For last couple years I have used a Garmin NUVI 550 with a ram ball mount. I saw another thread that PapaSkeeta did and got me more excited about a tablet and Oruxmap style. I stumbled upon the Lifetime Trail Maps site and wound up buying it with the Samsung Active2 8"tablet. It is pricey like the Adventure Pro but all things considered I believe reasonable for the maps when I think about how many hours this older non-tech savvy guy would take to learn and load the maps and trails. I have used it three times now. I originally installed it with a Ram ball mount off the passenger grab bar but it was too shaky and I figured that was not good for my vision or the tablet. So I made a flat tube steel bar with a custom mount of the Ram Cradle mounted on the passenger grab bar. BTW the Ram cradle has the POGO pins in it to give it the power supply while installed. It is now firm and stable, within reach and easy to navigate. The maps have a 'night mode' which is nice as the regular screen is too bright at night.
I have the Garmin for sale with the mounts and 48 states TOPO if someone interested just send a PM. The NUVI is a hybrid GPS that can be vehicle mounted or hand held.