I dont think so because with CR123's it will run until you have to look into the optic to see any light at all, and even a pair of dead CR123's will put out atleast 3 volts combined. All of my other regulated lights will run right until the batteries cant supply any more juice.
It may not be an intentional design characteristic, but it makes the XO3/T3 perfect candidates for unprotected 17670 cells.