Hi Bob and Phil (long time Phil)
We've been a few times with GPS and effectively let the boys use map and compass while the adults hold the GPS. This has worked well for review of how they did and on a couple of occasions refocusing on where they boys thought they were going vs. where they thought they were. (As in the last time it was getting dark and they were about to take a spur that would have put them 15 miles away from the destination that was otherwise really close. As such, it was a good tool to ask them if they really knew where they were, and refocus them on finding their location and destination.)
Your call. If your navigator doesn't know how to read a map, the GPS isn't going to help because it won't have the granularity on precisely where to turn.
We're headed back this year and will do the same thing.