Andrew,

I have the 3HP Gorilla in a relatively smallish shop (approx. 1 1/2 car garage). It's about as loud as any other tool (less than the DW735 planner though) but not more so. I leave it on for more than 10 minutes at a time w/o hearing protection without being uncomfortable. And the most important measure is that it's not to loud for SWMBO sitting in the house fairly close to the garage.

Performance wise, it's great.

Chris