The Axiom subs are great subs I am running three of them two 175's and one 350. I have been very pleased with them once I got them setup right (placement wise that is). I am not familiar with the HSU subs, but have done comparisons against Velodyne, Mirage, and JM labs. I could not say with any definitive certainty that the more expensive JM and Velodyne sounded any better or made my system any better then the Axioms. The only factor that I could see as pointed out by spiffnme is price.