Well I really opened a can of worms with this thread!
In other news, I applied two rolls of the "quick roof" product to my floors this afternoon. Two rolls (32$ worth) did the whole floor front to back with a layer on the back seat and double thick on the thinner areas that needed it.
Went on easy, very sticky and so far smell is not an issue (I suspect having a foil side keeps most of that in anyway). Also appears to do a fine job reducing exhaust and road noise.
I'll report back after leaving it in the sun for a few hours on a hot day (or what serves for a hot day in these parts).