@phomchick, we’re of the same generation. While scraping the money together to upgrade from my first loudspeakers, the AR 4x, I set my sights on the Rectilinear III, which I preferred to the AR 3a (too veiled and soft), the JBL L-100 (too colored, forward, and brash), and the Bose 901 (terrible!). For some reason I never saw or heard the Dynaco A-25. Before I was in a position to buy, I stumbled into Sound Systems in Palo Alto, and heard the Servo-Static I (at $2000, WAY above my 1971 pay grade. I was in a hippy band, barely able to pay rent and eat ;-). I heard the 2000A and 1001 (both of which I found more transparent than the Rectilinear) and though I wanted the former, I decided to get a pair of the 1001 and a new set of Ludwig drums. Gotta prioritize!
The ESS TranStatic also has a KEF midrange driver, the B110 you mention. ESS briefly offered a model named the Super Quad, which used the RTR ESL tweeter and KEF B139 woofer in the same transmissionline enclosure as the TranStatic, with the Quad ESL in place of the KEF B110. It was their competition to the Servo-Static, but I never saw or heard a pair. I finally found "my" speaker when I heard the Magneplanar Tympani T-I. I bought my first pair in ’73, and now own the last version of the Tympani, the T-IVa. The new Magnepan MG30.7 is an updated version of the T-IVa. I heard the 30.7 on the tour last year, but in a terrible room, at Echo Audio in Portland. One of the worst sounding rooms I’ve ever been in! Wendell Diller knew it, but what could he do?