I had a friend pick up the 600C for me at OSH last year. My only complaint so far is that the display is very dark, not anything like the picture on the box and in the advertisements.

Here on the Texas gulf coast everything is displayed as dark green. I guess they think it is almost tropical here. On the display it is very difficult to see the details. When I head inland, things get lighter and brighter. Much better.
I contacted Lowrance and asked them how to make it brighter. They said "That's the way it is." I've adjusted brightness and contrast as much as possible but still struggle with it.
YMMV
Karl