The SB-3000 is two steps down from the SB-16 Ultra. The EP500 will sound as good as an EP800 with 6 dB less output. The 3000 uses a 13 inch driver compared to the 12 inch in the Axiom.

It probably has 1 or 2 dB more total output, but in the cabinet its in, the 3000 needs more EQ to achieve the deepest bass.

For my money, I would take the EP500 just for its music ability. The Axiom subs are not the darlings of the internet for their sheer output, but if music accuracy AND floor shaking ability is what you seek, look no further.