I don't run full range dynamic speakers, but, I've heard a few. I have heard decent sound, albeit, thin in bass, from a number of full-range driver systems. None would really work for large-scale classical orchestral music (certainly not for organ), but, if small ensemble jazz or intimate vocal music is your thing, these kinds of drivers can grab you by the ears with their immediacy in a way that most multi-driver systems cannot.
At the high end, I've heard systems with Feastrix drivers that were very good. A friend has a field coil Feastrix in an onken enclosure that sounds quite good. I heard a cheaper (though still crazy expensive) Feastrix in a commercial system by a company named Volti that sounded really good (looked fantastic too).
I recently heard a decent open baffle system built around a 755 driver. I prefer the larger 756 driver myself, though a tweeter is needed with the 756. I believe a Korean firm is now making knock offs of the 755, though again, I bet these are not cheap.
I recently heard a full range system (cannot remember the name) that had an acrylic enclosure that looks like a big gold fish bowl. The single driver was by the Taiwanese firm Tang Band. This system sounded very good for the money. The Tang Band full range drivers are quite inexpensive, compared to the likes of Lowther drivers, and sound very good.
I have been very impressed with multi-way systems that are built around full-range drivers. The Horning speaker company uses Lowther drivers for the mids and highs, while using some other drivers for bass. I heard a terrific system by a company named, if I recall correctly, Surreal Sound, that uses a Tang Band full range speaker for the mids and highs. I actually prefer these systems that supplement the bass of supposedly full range drivers to systems that only utilize a single driver.