I don't think it is quite that simple Chakster.
As I see it, all things being equal (which they never are unfortunately) there are simply more compromises to be made with mono cartridges than with stereo as a result of the 3 different types of grooves to be played with mono (very early 33 RPM pre-microgroove mono, microgroove mono and "modern" mono cut on a stereo head) as opposed to the one groove formation to be played with stereo cartridges.
With very early pre-microgroove I think it is quite possible that a larger 1 mil conical may actually give the best performance in terms of dealing with the wider groove. On the other hand, the line contact or microridge (on a mono cartridge with adapted vertical compliance) would be very likely to provide optimal performance with more modern monos and recent reissues cut using a stereo head.
I'd be reluctant to play the latter using a so-called "true mono" cartridge with no or very limited vertical compliance; Miyajima does not recommend playing "stereo" records with their mono cartridges and I see no reason to take a chance playing a modern mono reissue cut using a stereo head with a cartridge like that even though some say they have done it successfully (some also say they haven't if you search the net).
And JCarr admits himself that a LC or MR is more likely to drag along the bottom of the groove in earlier wider groove monos and/or hit dirt or damage in that area leading to more noise in playback.
I think one should also distinguish between modern stereo cartridges that simply bridge the channels to provide "better" mono playback vs. modern mono cartridges with adapted vertical compliance purposely designed with 2 coils that are oriented to both grossly reduce and/or eliminate (the purists will always argue) reproduction of any vertical info/noise while at the same time eliminating the chance for hum/noise issues when used in a typical 2 channel setup.
In my experience, the 2nd (whether it has a line contact or decent conical) is much better at mono playback than the first whether it is regarded as "true mono" or not and these mono cartridges are really the swiss army knife of monos for users wanting one mono cartridge to play all their mono records.
As most of my mono vinyl is in very good shape and I have only a handful of monos from the pre-microgroove era I am tempted to retip my AT 33 Mono (aluminum cantilever and nude conical stylus) with a boron cantilever and MR stylus at some point. I think the results would be positive on most of my collection, but not necessarily all.
But I don't really find it wanting with the conical and still prefer it on the same table on an inferior arm (with both cartridges gain optimized also using the same phono stage) compared to my much more expensive/prestigious stereo cartridge when playing both vintage monos (to be expected) and modern mono reissues (some would argue or take the position not to be expected).
For the super hardcore purists wanting to extract the most from large mono collections, I can see the need for 2, maybe three different mono cartridges.
You could take the same position on stereo cartridges but the argument would be much more about subjective preference as opposed to technical merit in terms of actually retrieving the info from the grooves.
As I see it, all things being equal (which they never are unfortunately) there are simply more compromises to be made with mono cartridges than with stereo as a result of the 3 different types of grooves to be played with mono (very early 33 RPM pre-microgroove mono, microgroove mono and "modern" mono cut on a stereo head) as opposed to the one groove formation to be played with stereo cartridges.
With very early pre-microgroove I think it is quite possible that a larger 1 mil conical may actually give the best performance in terms of dealing with the wider groove. On the other hand, the line contact or microridge (on a mono cartridge with adapted vertical compliance) would be very likely to provide optimal performance with more modern monos and recent reissues cut using a stereo head.
I'd be reluctant to play the latter using a so-called "true mono" cartridge with no or very limited vertical compliance; Miyajima does not recommend playing "stereo" records with their mono cartridges and I see no reason to take a chance playing a modern mono reissue cut using a stereo head with a cartridge like that even though some say they have done it successfully (some also say they haven't if you search the net).
And JCarr admits himself that a LC or MR is more likely to drag along the bottom of the groove in earlier wider groove monos and/or hit dirt or damage in that area leading to more noise in playback.
I think one should also distinguish between modern stereo cartridges that simply bridge the channels to provide "better" mono playback vs. modern mono cartridges with adapted vertical compliance purposely designed with 2 coils that are oriented to both grossly reduce and/or eliminate (the purists will always argue) reproduction of any vertical info/noise while at the same time eliminating the chance for hum/noise issues when used in a typical 2 channel setup.
In my experience, the 2nd (whether it has a line contact or decent conical) is much better at mono playback than the first whether it is regarded as "true mono" or not and these mono cartridges are really the swiss army knife of monos for users wanting one mono cartridge to play all their mono records.
As most of my mono vinyl is in very good shape and I have only a handful of monos from the pre-microgroove era I am tempted to retip my AT 33 Mono (aluminum cantilever and nude conical stylus) with a boron cantilever and MR stylus at some point. I think the results would be positive on most of my collection, but not necessarily all.
But I don't really find it wanting with the conical and still prefer it on the same table on an inferior arm (with both cartridges gain optimized also using the same phono stage) compared to my much more expensive/prestigious stereo cartridge when playing both vintage monos (to be expected) and modern mono reissues (some would argue or take the position not to be expected).
For the super hardcore purists wanting to extract the most from large mono collections, I can see the need for 2, maybe three different mono cartridges.
You could take the same position on stereo cartridges but the argument would be much more about subjective preference as opposed to technical merit in terms of actually retrieving the info from the grooves.