Where I see this useful is at ranges where one has predictable morning to afternoon velocity changes. Out here on the Pacific coast we get a predicatable thermal sea breeze. Mornings are calm, and then the sea breeze (from the West) kicks in pretty reliably. Dialing the distance with a know quantity of wind might be useful. But then, if you know what the wind is likely to do, one could just keep a click chart, which as you say, is far less expensive than $100.00.