Originally Posted by bridgman
...the only thing you give up with HP drivers is ... ability to use them in a typical 2-way speaker.

Blame it on coil inductance; larger coil diameter and more turns than the standard 6.5" woofer coil. Inductance increases as the square of both.

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