The ACR Firefly is definitely good. I used an earlier version, the 4f, to pinpoint locations at night on several occasions for helos. Worked like a charm, as do signal mirrors, even in untrained hands.

Our SAR group found, as the result of a series of controlled tests, that an individual on the ground increased the chances of detection considerably by moving - jumping up and down, waving hands, and the like.

I would surmise that the strobe function of an EDC light would be useful - better than nothing at all, but not as obvious as a Firefly...