I have heard of it for years, but have always wondered how many SAR folks have the tracking ability to pick "your" print out of all the others on a lot of trails. (Using Vibram as an example, there are a jillion Vibram track on just about every trail I have seen in the last thirty or so years)

If one is going to do this, I would suggest cutting a notch out of one part of your boot soles, that would make "your" print different than all the others out there...