Sail cloth has a pattern to it, kind of raised places like slubs... not completely smooth. I'm pretty sure all stock soft tops are sail cloth on '09's, but I could be wrong. I'm guessing you are wanting the Dynamat for the floor boards? Never heard of anyone doing that, and yes, I'd think it would trap and hold a lot of water under it, if the Jeep gets caught in a shower, etc. If you do decide to try it, I'd use FatMat instead, it's better and less expensive according to several folks I've talked to who have used both.
Is this your first convertible? None are especially quiet, in my experience. I have a sailcloth top on my TJ, and there is definitely wind/noise, but I don't even really notice it, it's just another joy of driving my Jeep, for me
Oh, where are my manners? Welcome to the forum, don't forget to wave