i think the preference of hearing mono from a single speaker and stereo speakers is much related to how acoustically dialed in your room and speakers are. and specific set-up differences. so the variability of results will reflect room differences.
in my case i have a 4-tower speaker system and need both bass towers to be working to get full frequency coherence. plus the room is really dialed in so my phantom image is epic. not all phantom images are created equal.
i have two arms with mono cartridges (Miyajima Infinity 1.0mil stylus and 0.7 mil stylus) and listen to a fair amount of mono vinyl and digital. love the mono, both early wide grooves and later stereo cutter head mono’s.