Those CTS 4's were a Bear find, and were very close to what were in the original Bose 901s; they were pretty good full range drivers for their day. Not much below 100 Hz, not much above 4K, but pretty clean within their range. To my knowledge, they were never used in the WoS, though we tried a number of configurations including sideways line array monitors with nine of them in a slant front boxes kind of like footlights. Interesting, but not successful.
The single CTS cube speakers were pretty damned good full range systems. I demoed a system for John Curl once with Dynaco tube preamp and Stereo 70 power amp driving a pair, and it was a real ear opener for John. He really "got it" about trying to keep crossovers out of the critical mid band if possible to maximize articulation.
The JBL 2105s were just about the best midrange cone drivers of that era, but you'd really want to put a tweeter in at about 3,500 to 5 K depending on how wide a listening sweetspot you wanted.
Hopefully, each driver is in it's own chamber so the back waves are not interfering.
With really good full range speakers, you can be pretty happy without deep lows or sparking highs, and you can add a sub-woofer and a super tweeter if you want. They get to sounding like electrostatic speakers, though not quite as quick, because of the improved phase response with no nasty crossover phase distortion in the critical mid range where we are genetically most sensitive to sounds.