Well, OP seems to have disappeared. But, I’m a bit confused because I see ACC and also OC as suppliers.
I live in Alabama. ACC is an AL company. I went to there main office in the early 90’s and purchased a carpet for. Third gen F body. The quality was far better than the OEM stuff, backing and all was thick!!!
I will be taking the hour drive to their facility in Oxford AL to purchase new carpet for the driver/rear seat area of my 87 Burb, when I get to that point. Their stuff is top notch for sure. I think the kill mat is a needed step in one of these old Burbs, so wouldn’t be as concerned about the mass backing if doing so- but I am interested to see a comparison between the two- not sure they had two options back in the 90’s when I last purchased, there was no sound deadened like kill mat back then!