To really, really stay on top of a brushpile, I think you have to use a marker buoy. Personally I'd rather keep my eyes on the water and my fishing line, rather than back and forth between the line and a GPS. Paint your marker buoys grey, so they aren't so obvious. I also agree the Garmin GPS system is pretty dang good. My 498C is probably 6 or 8 year old technology, and it's dead on getting there. I never rely on it to keep me over a brushpile though.