Dead reckoning and legacy GPS units without the detailed maps or with outdated database (because they are so hard and expensive to update) are the main culprits.
In "my" airspace its not location that is the problem, its activation times. Military airspace only active intermittently, and on weekends. Do any of the iPad style maps use NOTAMS to only display active RAs?
Sunfish - would it be less of a concern if it was used as an educational/awareness tool rather than enforcement/punishment one? (I know, flying pigs and all that).