Dan:
The past three months Marda and I have used a Lowrance iWay 500C.
We feel extremely well pleased with it.
The large screen is very nice.
It's very user-friendly.
It does not know about low clearances, so we still check the tables in the front of the Rand-McNoodle.
It also does not know about hazmat routes.
When we encounter a required hazmat bypass or detour, we do what the signs require, then the GPS gizmo promptly figures out the new route.
The same thing applies to any other detour or deviation.
Rarely do we stumble onto an unanticipated hazmat bypass.
Using GPS is not only very helpful but also super-cool and a real hoot.
Our gizmo has already paid for itself several times.
Good luck!
Doc.