Opinions on Full-Range/single driver speakers

I am considering a DIY project to build a pair of single driver speakers. My current idea is to put Jordan JX9s into Transmission line cabinets. I am a competent woodworker and there are lots of plans on the internet.

I do really value the opinions of you audiogon members out there with lots of listening experience so I am curious what your opinions are on single driver speakers. If you can also comment on wide-baffle versus narrow baffle designs, that would be helpful.

My front end is a Monarchy tube DAC 25 with Matsushista tubes and DIP Classic, coupled to an AYRE DX7E, all interconnects and cables are DIY magnet wire. I am currently using Green Mountain Europa's and a modified Paradigm subwoofer.

After enjoying GMA's and experiencing time/phase coherent sound, I started looking at other options for coherent systems. It seems the simplest design is a good full range driver (no whiffle cone) in a TL or QWL cabinet.

So your opinions are appreciated. I would prefer if you did not advise me to purchase your favorite speaker as that is not the type of information I am seeking.

Thanks in advance for your time!

Drew.