Mono is a bit special to me as I have no hearing in my left ear, and cannot perceive stereo. The London Reference has been a great favourite purely for its sound (I can't speak to imaging and suchlike), and I am curious as to whether a Decca mono cartridge would be as special to my ear.
Now having discovered that a SS Hyperion gives the Reference quite a challenge, another possibility for the same cost as the Maroon would be a SS Zephyr MkIII in mono. Possibilities!