I would agree that noise reduction is minimal, I only did it to reduce the buzziness of the exhaust / floor. If your wanting to make the car quieter, I wouldn't bother !!
I think the use of Carpet underlay is a better option. For one its lighter and its also much lighter and easier to remove. Have you ever tried to remove Dynomat!!!!!!!
But in all honesty, I'm not sure how much difference it would make with my exhaust, maybe just water spray in the arches and a reduction in squeaks.