I've mainly been a lowrance/navionics chart user, but am looking for a decent handheld to use on my little boat out here in the middle of OK. My main lakes are Canton, Sooner, and Carl Blackwell. Does the Garmin chip (I think it is their Southwest region one) include any useful topo info on any of these lake, or should I just save myself the $100 and live with what is on their basic GPS. I'm looking at the GPS 78 from Amazon for a bit over $160.

Pissed Lowrance discontinued the I-Finder H2O, that was a simple and reliable chartplotting handheld, even if you could never find the 12V adapter for it. Now they don't even sell a handheld GPS