Way late to the game, but I'll add my two cents.
"Full range driver" is a misnomer, as no driver is truly full range. For that reason, folks have started to refer to them as "wide-banders."
The advantage of wide-banders, as other have alluded to, is that like coaxial drivers, they approximate a point source. They also tend to be punchy, with good transient response, and relatively easy to drive. The down side (in addition to their not truly being full-range) is that they often have annoying peaks (e.g., the Lowther "shout").
Recognizing that there is only so much bass output one can wrestle from them, some manufactuers are now adding woofers below them; I refer to this arrrangement as "augmented wide bander." One of the difficulties of this arrangement is finding a woofer that will "keep up" with the wide-bander; I daresay Danny's servo subs are an excellent choice.
As for the wide-banders themselves, not all are created equal. Some are awful, some are superb (the Voxtive being the best I've heard by a long shot), and most fall somewhere in between those extremes. In my experience, many speakers (not just those based on wide-banders) suffer due to the choice of driver. Certainly a good cross-over and well-designed cabinet (or lack thereof, i.e., open baffle) can optimize the performance, but one cannot make a silk purse out of a sow's ear. I am very intrigued by Rich's approach to digitally correct certain characteristics of the Dayton, though I have no experience with this driver, nor with the correction.
I recently reviewed a very well designed "augmented widebander" which uses a Tangband on top, and six 10" woofers below in a diploe, slot-loaded configuration. (
http://www.dagogo.com/Print-Article.asp?hArticle=1115) The dipole configuration necessitated a separate amp and Eq but IMO, this is actually a benefit, not a deficit. Danny has taken this approach for some time now, and I am continually surprised at how few designers have caught on to the benefits.
I am delighted that Rich, Danny and their colleagues are building the Monolith, as the more such speakers there are on the market, the better for the consumers (i.e., us). I especially applaud Rich for the novel elements of his design, and eagerly await the opportunity hear it. Perhaps if I'm nice to him, he'll let me review it.
Regards,
Larry
