Ok, sorry BI65ND i'm not trying to pick a fight here so please don't get me wrong...I'm just speaking from my own experience here but yes a cheap speaker will always sound like a cheap speaker...BUT... I had a set of option audio OA60C's in the front of mine a fair while back & everyman & their dog was trying to talk me into sound deadening which I then believed to be a fad thing & everyone was doing it because everyone was doing it. I ended up talking with a great mate of mine that is a real pro with audio stuff & he convinced me that it was the way to go so I gave it a shot on one door. Once it was done I did the left/right channel thing & I swear blind that I had 2 entirely different speakers running. The side I deadened & sealed was so much richer, fuller & the mid bass was there compared to the right one undeadened which was all high pitched & tinny with bugger all mid bass. So for me there is no contest if it should be done or not no matter how good or cheap the speaker set up is...it just works.
Now as far as the option audio deadener is concerned, there is absolutely no issue with it sticking or peeling off. I have this brand in my car & have had for the last year & 1/2 and it has not lifted, peeled or fallen off because I prepared the surface properly. The ones you have seen where it has come off I will bet that it was just slapped on with no surface preparation whatsoever or at the least not done well enough.
I have a mate that lives around the corner (par14h
http://www.auslancer.com/forum/viewtopic.php?f=4&t=130) & he had some of the same deadener put into his boot from a local audio joint & they just slapped it on quick & dirty, needless to say it has since fallen off because of no surface prep.
Yes it adds weight, thats the point of it & how it works but to do just the doors you might be looking at an extra 5kg at the most so it's not really too much of an issue.
I've done my doors, the entire boot area & the boot lid, am carrying 2 amps, a set of splits, 6x9's(atm), a 12" sub & box & heavier guage wiring(probably an extra 40-50kg) in my old 4g15 & there is no issues with it getting up & going but the quality of sound is there & thats what I wanted for mine.