I used impact guns to disassemble and reassemble stuff that are clearly in the "Do not use impact gun" territory. It is not the impact gun that does the damage, it is the user. Short bursts is all you need to losen the stubborn fastener. If you are going to sit there and hold the trigger until something gives, well, that is not the use of the impact now is it? Using the hammering effect also helps with NOT rounding off bolts and nuts. And finally, noone mentioned the size of the impact gun. For plugs, I would reach for my 3/8" butterfly impact. Not the 1/2" gun I use for lugs, suspension bolts, the big stuff.