My old TomTom is wearing out and it's time to replace it and get a second on for my wife. I can get xxl540 or via 1505 with rewards points, but I'm not sure which to get. The larger memory of the via seems like it would extend the life of the gps, but I've read that the via can not be changed while the car is in motion. That's a deal killer unless it can be turned off. Any opinions? Thanks. Ron