I have a new GO 600 that has liftetime USA, Canada, Mexico maps and a subscription to the USA, Canada maps. Is there an advantage between the maps, other than the Mexico coverage or smaller map file size? I moved up from a GO Live 740 to the GO 600 (not very thrilled with the dumbed down 600's limited features/versatility and slow touch screen response time). I will gladly pay the subscription fee if there is a distinct functional benefit to the USA, Canada map.