Yes but even the lighter tiles are at least 3 pcf. You can get those in almost any home center. They are thinner 5/8 so you may have to double them up. But yes the thicker more dense materials will always be better. And your right you need to know what the tiles made out of. As far as better? All I know is I can build a box, drop in the tiles, and have it end up within a 1hz-.5hz of my design spec. tuning frequency.
Rob