SatNav recommendations

I have just had a look at updating the maps in the factory SatNav in my 2008 GU Patrol Ti. The factory unit is a VDO Dayton which uses whereis MS5200 maps on an SD card. The price of the new maps on the whereis website is $199.00, at that price, prompting the question of what other SatNav units are out there.

The current SatNav has a screen of approx. 7 inches which is a nice size, so if there is anything out on the market this size, it would be nice. It also has the factory rear view camera, which I would like to keep compatible with the new SatNav unit of possible. I would plan on pulling out the old unit and replacing it with the new unit, depending on how easy it is to get the old unit out.

The unit would be mainly used for on-road use, as I use my tablet with OziExplorer on it for off-road mapping (but off road mapping in the unit would be a bonus). I do like using the map in 2D view zoomed out on long country runs, so would like a unit that has reasonable detail (e.g. upcoming town names etc.) at that zoom level. Also the usual Turn-by-Turn navigation. I know a number of devices now how Lifetime Maps, so this would also be a handy feature.

Does anyone have any recommendations of units that would fit my criteria?