I am using an Oregon and it's also very easy to turn the overlay on. As long as the garmins are not able to switch on/off the display of certain types of POIs the creation of specialized overlay maps will be a good workaround for this missing feature.That sounds interesting (and an incentive for me to define some bus route relations for nearby lines). Have you documented your process? I have yet to create or use any map overlays.I'll try to get around to documenting my procedure. For the overlay, I simply created a non-routable transparent map with a higher draw-order than the main map. Using an eTrex, it's quite easy to turn the overlay on and off -- I'm not sure how easy this is with other Garmin units.