advice for mono cartridge

In practice, who is going to have more than one mono cartridge mounted up and ready for use?  Only a mono-phile who hates stereo, and there's not many in that category.  So most of us will choose one mono cartridge and live with it.  I already mentioned the factors that governed my own decision; I simply do not own any LPs cut much before about 1953-55.  And I don't play rock and roll 45s, either. (Nor do I know what would be optimal for those.)  If you're a 78-nick, you make a different decision in favor of 1.0mil conical or whatever.  I bought a Shelter 501 mkII mono, and I stopped worrying about it, not that I think my choice is the absolute one and only valid one.

I see your point for 78s and late 1940s and I don’t know about 45s of the 50s, but I own nothing in any of those categories. 0.7 mil or exotic nonconical stylus is fine for my needs. And I do insist upon 2 channels of mono output, however it’s achieved. That’s how I approach the mini-dilemma. Plus my preamp must have a mono switch.

Chakster, To answer your questions:(1)  I am not really sure your assumption about compliance applies to ALL true mono cartridges.  The fact is that vertical compliance in a mono cartridge is irrelevant, since the motor does not respond to vertical motion at the stylus by producing an audio signal.  Ideally, the cartridge is totally inert to vertical movement of the stylus. I don't know whether that is always true in practice. "Modern" mono cartridges are nearly always stereo cartridges that have been internally bridged to produce a mono signal; therefore those typically do have vertical compliance.  (Bridging ideally cancels signal voltage due to vertical motion of the stylus tip.)
(2) I have read that fancy stylus tip shapes are irrelevant for mono.  JCarr has argued otherwise, I think.  Miyajima seem to think conical is fine for mono in their true mono cartridges.
(3) In my opinion, the definition of a "true mono" cartridge is that it has one set of sensors that work only to respond to lateral motion of the stylus tip, and often they have only one pair of output pins.  Compliance or no compliance.  There is no bible for this.

That’s valuable testimony. A dichotomy arises because if you switch cartridges then that brings into play the fact that you’re comparing two different cartridges. The mono cartridge might just be better than the stereo one. For each of us the outcome could be different. But you’ve stimulated me to do some serious comparing. One thing is for sure, mono LPs should be reproduced in mono if you want to get the most out of them.

If it's of any use to you, I bought a Shelter 501 Mono about a year ago.  Although I don't use it much out of sheer laziness, with the mono mode switch available to me, it's darn good, cheaper than some of the Miyajima's, and I have yet to hear a rationale for why "true mono" is going to be any better than a stereo cartridge bridged for mono, or a mono switch, for that matter.  One vinylista claimed that using BOTH a mono cartridge and a mono mode switch on his preamplifier sounded superior to either method alone; I have yet to verify that, because either method alone is SO much better than listening to mono LPs in stereo mode.

Stringreen,  Have you ever listened to a mono cartridge (of either type), or does your preamplifier have a mono mode switch and have you used it?  Because, after years of listening to mono LPs with stereo cartridges, I now would never think of doing it again.  Both my preamplifiers in (two systems) have mono switches, and I invariably hear a BIG improvement by just flipping that switch when playing mono LPs.  Much less high frequency hash, for one thing. I urge you to try it.  I own a mono cartridge, as well, but I don't always bother to use it for mono LPs, becasue I am so satisfied by the mono mode switch.

On the Miyajima website there is some useful information on stylus tip dimensions vis the vintage of a mono LP.  I don't remember it well enough to go out on a limb here, but I think I concluded that for "late" mono LPs, which is mostly what I own (no 78s at all, usually jazz from the mid- to late 50s), 0.7 mil is to be preferred over 1.0 mil.  But in theory, there is nothing wrong with using a modern exotic stylus shape.

As to the question of vertical compliance, I would not get hung up on that.  What might matter is whether the cartridge is designed and constructed as a "true mono" or whether it was built for stereo and achieves a mono output by bridging the two channels, internally.  The latter group of cartridges are by far in the majority.  The act of bridging cancels the signal that distinguishes between stereo and mono output. Only a few companies make true mono cartridges these days, Miyajima being one of them. EMT and maybe Ortofon also make true mono, and maybe also Lyra.  I say "maybe" because the makers are very ambiguous in describing the construction of their mono cartridges.  The Ortofon that you mentioned, for example, is almost surely created by bridging the two channels of their stereo equivalent.  But if you read their ad copy, you wouldn't be sure.  One benefit of the bridged stereo type is that you get two channels of mono output; I prefer that for driving my stereo speakers in mono.  With a true mono, sometimes you only get one pair of output pins, hot and ground.  This makes it awkward to drive a stereo pair of speakers in mono.  On the other hand, if you are a purist, you might want true mono, which would have no way of leaking high frequency groove noise into the phono stage. (Mono is in the lateral plane whereas stereo information is derived from vertical motion of the stylus.  If there is no stereo signal, as on a mono LP, then vertical motion of the stylus only generates noise from whatever dirt is in the groove.  You want to cancel that signal, which is effectively achieved by bridging but it is possible that a true mono cartridge might be superior at rejecting that source of noise. (I can't say, because I have no true mono cartridges.)

Finally, there is the question whether using a mono cartridge, especially the ones derived by bridging, is any better than using the mono switch that you may have on your linestage or phono stage.  There are varying opinions on that.  I don't hear any difference.