If you know someone with an IR camera from their work and you searched on a cool but sunny day, your light might be picking up enough heat from the sun to show against the cooler background.
That's a lot of "if's" though... Could be faster than metal detecting if you got lucky, but probably not as certain.
Too bad it wasnt a MiniM*g with a blinking IQ switch, then you could either find it or not care...
I keep saying I'm going to wrap my batteries with my name and phone number in case a good samaritan finds one of my lights... I'm sure I'll get around to it right AFTER I actually lose one!
Best of luck with searching!