I have a quad of each in identical cabs (VHT D412). The H30s have faster attack and more low end while having a sizzle (for lack of a better term) in the upper mids. The GBs have a little slower attack, but are very full sounding with exaggerated - almost syrupy mids. I prefer the sound of the GBs, but I wish they had the attack of the H30s.