I have the Sausage Fattener and it's great. Like most other things of this ilk, its effect can range to a very subtle amount of thickening to all out wave-sausaging. And also like most other things of this ilk, it's not something you'd want to slap across a master bus (unless it was a very tiny amount) and it's not something you'd want to slap across all of your instruments. I don't see a problem with reducing the dynamic range of one or two instruments in your mix, as long as it's contrasted with more dynamic instruments. It's a great on a drum bus to add a little meat, just crank it up to 10-15%. It's not going to sausage any waves at that level.