I don't know about the Luhr, but I'd go with a GPS over anything else. GPS is uneffected by waves, water current, wind, etc. and is a whole lot more accurate. The down side is that a GPS costs more. But the cheapest new GPS is going to run about $95, about double what the Luhr costs. But for that extra $40, you'll get the ability to mark good spots and return there again and again. And it will be useful for hiking and finding your car in those huge parking lots.
Just my two cents...