I just purchased a new boat, it has a Lowrance HDS-7 in it, but without a map card. I have searched this forum and it seems that with this system, Navionics card seems to be the go. However, I priced a Navionics Gold card for $454, and the Platinum one was only $519. It seems to me that the Platinum would be better value, but I would like some feedback from anyone that has the Platinum cards, and if the 3D maps are any good??