I am buying a second GPS for the front of my boat and I need to get a Navionics Hot Maps card for it. I will probably but a new Lowrance Globalmap 3600c IGPS (they are discontinued but you can still find new ones) which has the internal antenna for around $475. I use the Hotmaps Premium 2006 card with my current 3600c IGPS. I think I paid $119 for it. I see the new cards are around $149 and I don't know if I need the high end card. I see the Gold and Silver cards listed at lower prices. Any idea what the major differences are?

Any suggestions on a better unit for the money?