Mono Reissues and the Conical Stylus

Dave, interesting comparisons! And they align well with what I wrote. The mechanical aspect ie. stiffer vertical suspension seems to me still a very important factor.
Recently Shibata tips resurrected, interestingly at the top of the ladder. I principally assumed tha a vdH / Gyger Type I stylus or a MR stylus were "better than Shibata", that's the way they were introduced in the eighties. Maybe... it was already good vdH marketing - or the re-inroduction of Shibata is? However, from what I read about the new top AT MM cartridges, I somehow trust that the Shibata excel in optimizing the musical detail vs. amusical artefacts ratio.
The resurgence of conical styli, with the original SPU or DL 103 "cult" contains some arguments pro conical styli. Ie. a suggested geometrically much more complex pinching effect / movement of the "sharper" modern styli, including MR or Shibata. This would lead to spurious vertical movement as artefacts (more with these sharper styli than with conical styli), and is a claimed reason for the more relaxed "pro-music" way of musical tracing of these very traditional (and superb) cartridges.
Extending this line of thoughts... could mean that the "real" advantage of these sharper styli would stand out considerably more with a "real" mono cartridge like a Miyajima Zero, because the spurious vertical movements would not be decoded, or far less. And the lack of out-of-phase, vertical stereo signals would eliminate a source of intermodulation on top of these spurious movements.

Wow, some people need a higher dose of Thorazine. I could never hear the difference between styli in the same cartridge. I guess my hearing sucks. If you think you need a mono cartridge it is your money. I certainly do not having just listened to a mono copy of Art Blakey's Jazz Messengers. I am not about to spend money on what is most likely a meaningless improvement in sound quality that I sincerely doubt any of these people can reliably distinguish. Spurious vertical movements? I'm going to jump up and down on my tonearm to see if I can create some spurious vertical movements. I wish my d--- would have some of those movements. Maybe I should plug myself into a phono preamp. Any body try that?

'Maybe I should plug myself into a phono preamp. Any body try that?'
Sounds as if your already convinced but if you wish to, then go ahead.

My main point is: The difference I heard was as clearly audible as any I ever heard. Between a very good stereo and a "real mono" cartridge. It’s the kind of difference every non-audiophile hears, because it’s the difference between kind of fake and real life, it’s about musicality and direct connection to the musicians. I agree with you mijostyn that there is too much talk about micro-differences that are only relevant for audiophiles, which are not really relevant for the musical experience.
The rest of my post might be over the top of (your? others?) head, and / or you don’t like the difference to exist? I could understand that. I did so for quite a long time.
Regarding the conical stylus: The stereo cartridge had a very good line contact stylus, the Miyajima a 1um conical. The line contact to our ears didn’t swamp the electromechanical advantage of the "real mono" cartridge. Although it most probably would improve the latter, as Dave observed.
The review (Hifi News) of the 1um vs. the 0.7um version of the Miyajima hinted at even better sound with the bigger radius on "original" mono recordings. But the 0.7um is probably the safer bet, because it wan't harm any of the newer microgroove cut mono LPs (or mono reissues). I decided for the 1um because of the big stock of old monos in my family.

For as many years as I've been playing LPs I should know this.  But this thread helped me realize that I don't.

Early stereo LPs often contained warnings against playing with a mono cartridge.  Was that due to the larger conical mono stylus tip compared to elliptical stereo tip which might cause damage to the groove?

Or was it an issue with vertical motion of the stylus/cantilever?  I've read that true mono cartridges do not pick up vertical groove information.  I assume that is because of the coil configuration rather than the cantilever not being able to move vertically.  If it is the latter is that the reason it can cause groove damage?