Indeed, 1000 lumens in a Mag mean:
- overdriven leds;
- very much heat which cannot be dissipated by the Mag which is not designed for that;
- some flux lost by the poor quality of the small reflector of each led.
So: the leds will be less luminous after a few minutes (they will loose a strong part of efficiency, because led efficiency decreases while heat increases). After a few hours with such high stress, their life duration won't be the best...