Im sure the sensitivity rating is due to the output from the horn, not the woofer itself. That's one of the reasons Id love to hear one, id really like to know how well they blend. Probably pretty good considering the likely efficiency versus cone area differences.
That's actually exactly what it it //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif They call those "co-axials"
Adire's HE10.1 kit is essentially the same thing; HLCD mounted in the middle (co-axially) of a 10" woofer.