Mike,
I run the Navionics platinum chip on my Humminbird 997 and love it. I don't use the 3D feature a lot but those 1 foot contours are spot on and help me stay out of trouble on my trolling passes. I was amazed at how accurate the contours are on Winni, Sebago, etc... I think you'll be very pleased with the platinum chip if that's the route you go.
