I don't mean to horn in here, but I thought I'd describe my experience.
I got my carpets from AutoMat (autointeriors.biz). The carpet came with a pad (of some modern material - nothing as fancy as dynamat). Of course I can't compare my setup with Europa73's, but I'm satisfied with my carpet situation. One thing dynamat may be better for is if you get water in your car - it may not retain it like mine does. I wouldn't think it would make much difference in sound or temperature insulation. But then, I may have missed the boat entirely and dynamat makes more of a difference than I expect.