I think they should have never used the tar-like fabric material in the floor pans of our cars. You'll agree if you ever try to scrap this stuff off. To me , the material traps moisture and promotes rust. I have seen many W113's with rusted areas under this stuff. I'm not sure that the dynamat type material is any better. I scraped, cleaned , and repaired and painted my pans and used a thick, auto- jute padding on the pan area under the carpet mat areas, with a dynamat material only on the place where our foot mats are. If I had to do it all over again, I would probably skip the dynamat. I just don't think it benefits much. New carpet and a good jute pad is all that is needed in my opinion. I used the jute pad under the seat areas and under the floor mat areas only. All other carpet sections were glued. I did not glue the over the hump carpet piece, forward of the shifter, for easy access to transmission windows if needed. ( A tip from Bud's Benz) It helped make the car very quiet when driving. Trying to remove a dynamat type product would not be any easier. Using it sparingly as I did, is a safer bet in my opinion.
