Thanks for the input.
I really don't need auto routing. I have the TomTom receiver and software for my PalmT3, and although their routing algorithms leave a LOT to be desired it gets me where I want to go.
If the Garmin 76x and Lowrance Explorist have similar performance under foliage the deciding factor is the price of marine charts.
The $100 unlock fee for Garmin quickly adds up. We spend a few weekends a year roadtripping to different places and usually bring a boat. With Lowrance I can get a Nautipath map of the entire US for $99. With Garmin I have to unlock each region as I go. Last year Chesapeake Bay and Boston. This year Maine and NY Canals. Next year North Channel/Georgian Bay. Plus the home area of Lake Ontario. That's $400 to $600 in unlock fees for Garmin.