Not to design a whole room around this. Just if you insulate anyway, it's better to have it touch rather than hold it back. This and this alone isn't going to cut it. In the same post I referred to, he lists all the important facets of isolation. Or go to green glue site and they list isolation attributes, mass,decoupling,absorption,resonance and conduction. Now if you believe having something touching the inner wallboard will dampen,lower resonance, like knightfly suggests go for it. If not don't. It is free after all.
