No idea if they work bettter, but I doubt it. Sure they produce finer bubbles, but they are spread out over such a distance that it would be difficult to centre under the root ball. I'm going with the limewood. I have a big block already cut and drilled and ready to go.
Limewood Airstones
Limewood is an extremely durable wood, composed of very fine and straight porous grain. Each airstone is specially cut to maximize the number of minuscule air bubbles that are continuously being released into the water. The rugged, screw-in nipple ensures long life under high-pressure conditions created by powerful pumps.