Jason, the point Alan makes in his excellent article has been discussed here in the past and it's been pointed out that the lowest bass notes, which are played by a sub, are inherently slow and in no way can be described as "tight", regardless of the quality of the sub. Any tightness in the sound of a musical instrument playing a very low note, say in the 40-50Hz area, is due entirely to the upper harmonics which are played by the speakers, not the sub. As Alan again points out, a good demonstration of this is to listen to music containing a lot of low bass material through the sub alone, by disconnecting the speakers while keeping the settings the same as if all speakers were active. With a crossover in the 60-80Hz area(possibly steepened by also setting the sub's internal low pass filter to about the same frequency)what's heard certainly can't be described as "tight", "musical" etc.
