Archeologists 
artifacts… JK. Turning up the speed on the head to compensate to a stronger laser substantially decreases the quality of the engraving.
For engraving the less power in the laser the better. To be convinced of that fact just look at some of the amazing photo engravings our very own @Bulldog achieved with his diode laser on tile.
So bigger and stronger more powerful is not always better.
Cheers
Sasquatch