@ Neil
Yesterday I had a 500 km trip back home. The terrain differed from flat and open fields to mountain passages, many trees, tunnels,towns and a few cities. In driving conditions the best accuracy was 15 m. and this was best case scenario. Usual accuracy was 35 m + and that not depended from terrain at all. In open field, clear sky to hear Lost satellite reception on each 5 minutes is too much. So many times have left the road on gps screen that for me is a really bad feel to relay on gps in certain situations.
The bad thing in my case is that even go back to 3790 the accuracy is still questionable.
So count me in camp 2 and soon in camp 3 because I'll buy 3597 immediately after its appearance on local market. May be and because of above I'll take harder way and will format unit and will start from ground 0.