I started out on Navtor, but switched to NavBox some years ago. I echo the comments of the others, very pleased with it and nice people to deal with. I get the update once a month. The whole thing is very good and very reliable.
Mike C
I also spoke to them at the PFA Rally. The Ipaq s/w looks good but I am not sure the screen is sufficiently large and I think the battery life is only about 2 hours. I wonder how hard it is to power it from the aircraft systems, connect it to the GPS and not have too much spaghetti in the cockpit?
Rod