frugel-horn.com is an excellent source for full-range horn designs, as well...
And yes, throwing a high-excursion, high-powered driver in something like this sort of misses the point //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif I have two 6.5's with 2mm of Xmax in a 6' tall horn, and with less than 10 watts they'll extend down into the subbass range...can't do that with a ported enclosure.