I don't own an RRT-3 yet, but I guess it's fair for the temperature protection circuit to shut the flashlight down, or at least to a dimmer level, well before the claimed 80 minutes @ 1200 lumens.
They are only claiming that the battery will last 80 minutes @ 1200 lumens.
I don't think they are really claiming that it can run continuously for 80 minutes @ 1200 lumens.
We do have to consider the heat build-up...