Well, it was Mines that mapped it. They will have locked the map though, the same as Toyota do once they have set it.
Power gains over stock are considerable, the fact that it boosts to 1.1bar explains that. Gains for BPU will be mostly mid level linearity. It is a more agressive map meaning that it will pick up better and give better throttle response. Up top I don't think you will see too much of a gain as the turbos are really at their limits with BPU. You might see a few HP more, much the same as a piggyback ECU.
I've not known of any cars blowing with the Mines ECU and I certainly never had any issues with it. As said though, I wouldn't drop any lower than 99RON. That's the same as I would say for the stock ecu though.