I had this very conversation with the guys at 'The Sound Deadening Shop' just down the road from me yesterday.
He says the Audio guys love the Dynamat brand, and if your spending £0000's on audio then you'd want the best materials around the best speakers to get the best sounds.
The converters love Silent Coat, as you get a lot more coverage per £ spent.
I was in buying a couple of Dynamat sheets for my new door cards, just following what Absolut5 did on the existing card when they did my sounds, same material same place was my mantra.
If you look at the prices of the two this will make sense.
Thanks! I'll take a look into this. I hadn't even thought about upgrading speakers etc when mine arrives but everyone seems to do it. Hmmmm. More pennies haha.