I've heard several systems with their drivers, including their Ampeggio system, and I like their sound. I have also heard a few other systems based on full and wide range drivers that I like a lot. One of the best sounding, and not crazy expensive systems is the Charney Companion single driver system with an AER driver in a quarter wave back loaded horn cabinet. It delivers a very clear, coherent, warm and full sound with reasonable bass.
Songer Audio also has a great sounding single driver system that employs a field coil driver. They also offer a two-way system employing that field coil driver and it sounds great too.
My favorite full range speaker is the Jensen ERPI M-10 field coil that was built in the 1930's and there are working models that sound fantastic, particularly if they are supplemented on top with a tweeter (i.e., run full range but with a tweeter supplementing the output way on top to counter the narrow dispersion that would result from a 13" driver operating full range). The big downside is that a matched pair of M-10s is not easy to come by and they are expensive.
This past weekend, I heard a stereo pair of Western Electric 728 drivers (also ancient) in Karlson cabinets. This was thrown together just to see how it sounds, and with no further tuning (e.g., adding cabinet damping), the combination sounded quite good--very dynamic and coherent sounding.
I like systems employing full/wide range drivers used in multi-way system, like the M-10 with tweeter mentioned above. The Cube Audio Nenuphar Basis system, employing their proprietary full range driver and a powered woofer is a great sounding example too. I am a fan of Pure Audio Project open baffle speakers that employ wide range drivers and woofers for the low end (they even have models with Voxativ field coil wide range drivers).