I have hds10 & 8 with Insight on both units. I looked at the Navionics chips for Ky. Lake and Insight has a lot more detail for my particular lake. If you get 2 units with 2 different maps they will look different at both ends and be a lot more confusing. Especially with GPS waypoints.With Navionics you have to buy 1 chip for each unit. They will not share maps on the network.Same thing for Insight maps. They will not share maps between the units.The one advantage with Navionics is you can buy another program called NavPlanner 2 and manage waypoints. I have NavPlanner 2 and it is hard to figure out. I use OzExplorer for all my waypoint managment.Just what I am use to .