On a general point, whichever satnav you use...and I know most people here won't need telling this - a satnav is only a navigation tool, it isn't a replacement for the driver's brain. Just like using a map, or reading road signs, or following the caravan site's own printed advice, the driver still needs to look out of the "big window" and think about what they're doing. I get very frustrated at the usual crop of newspaper headlines like "my satnav made me drive into a river" - no it didn't, YOU drove into the river! Having said that, as I've previously said, I'm a real devotee of the technology and get really grumpy when Mrs Gozza has one of her occasional luddite purges and insists we do without the technology and navigate the "old fashioned way" - especially as that usually means getting lost!
My nusual technique is to look at a map and decide what I think is the best route, then programme the satnav and see how it compares. If the satnav and I agree, we're good to go - if not, I go back to the map and work out why the we disagree - usually it's because there's a road on the way where I know there are usually huge jams (A31 around Ferndown, anyone?) where the gadget has just seen a dual carriageway and assumed it's a fast road. I can then adjust the satnav's route so it and I agree on the best way! Then I can get in the car and concentrate on driving, and not have to
a) try to remember the route directions
b) take my eyes off the road to look at a printed map
c) keep waking Mrs Gozza to check the map