Re: Best handheld GPS for lakes
If I'm not too late making a suggestion, I would choose the Garmin 478.
http://www.tigergps.com/garmingpsmap478.html
I can only speak from fist hand experience. The 478 is the only GPS I know, but it has performed well for me. I take it from my truck (for drives to unfamiliar territory) to the boat (for navigation into the unknown) to my bike (for long rides into wilderness) and throw it in my luggage (for vacation). It's awsome.
I've been most impressed with it's marine features. It has data base of marine info in it. Switching to marine mode will give you a lot of info like channel markers, bouys, hazard, contours and depths. The features are abundant. You can expand it by purchasing a data card. They have a card of inland lakes (region specific). I also purchase the sonar unit, so it doubles as a fish finder. Accurate speed for trolling or whatever.
It's a couple years older, but for that reason, you can find it even cheaper than the link I posted. Good luck.