From what I've seen on my v4, Axiom is continuing the tradition of letting the woofer response attenuate naturally on the low end rather than limiting it with filtering. Simple theory will tell you this is bad because amplifier power is being robbed to move a small driver non-linearly and it could get damaged from thermal or mechanical fatigue. In practice however, the truth is more complicated. First, the woofer remains linear for its specified range and SPL. Second, the woofer does not get damaged mechanically or thermally even at the peak specified levels. Third, adding a filter to limit low frequency behavior likely negatively impacts The Family of Curves. Fourth, such a filter would unnecessarily add cost.

I've found with any of the passives including the M100, low frequency performance improves with the addition of a sub. The actives are a different beast. For music, the addition of twin 500s fed off each DSP make no difference in my 1800 cu. ft. living room which is open to the rest of the house. The bass is absolutely a wonder and I cannot say that about any passive in the same space. The active, signal level filtering has brought out the best in all the Axiom drivers and there is nothing more one could ask for with regard to speaker response.

House of the Rising Sone
Out in the mid or far field
Dedicated mid-woofers are over-rated