Another FF Question

A neighbor down the street wants to put a new FF/GPS on his 12' Gregor he mainly fishes freshwater and Crabs. I suggested the Humminbird 597ci HD DI he looked around and asked what about the  Helix 5 DI/GPS. Any big differences in the two?

The 597 is a older model,and if he finds one they are very expensive,the helix is just a newer model either one would work.yes I'm probably the only hummer here