I can't hear much of anything below 22hz though I can "sense" vibrations or what some writers would attribute to our ability to sense changes in the pressure gradient of the wavefront.

Yes that data below 16hz is abnormal, likely caused by windnoise.

Chuffing sucks because it makes higher frequency noise. Its the achilles heal of all ported subs and the main reason I also own several sealed subs. While ported subs have higher output there is a price for everything. Output below 22hz is contributed by the port not the driver so it can be noticeable at loud volumes down low. Still, the large single flared vortex port in the EP500/600 produces much less noise than the chuffing generated by subs with tri-port or slot port designs.

John