I've never heard anything like those speakers, but I know someone who did hear them at Dayton DIY2008. I trust his judgment and ears, and he said they were the best speakers he heard that day. He was intrigued by the sound of the opposed omnidirectional mids and monopolar tweet combined that way.
If Paul Kittinger was responsible for the design of the TL bass module, then it will be very good. A tapered 71" long line, folded into that box looks to me like a very difficult build. There seems to be few, if any, right-angle joints.