mono cartridge vs stereo

Lots of the music I want to listen to is in mono. At present I use my stereo cartridge with the mono button pressed on the phono pre. I can't find much on the differences in this vs dedicated mono cartridge. Any insights/experience would be appreciated.
A mono only cartridge will bring a significant improvement. I have two arms on my TT, one is stereo the other mono. I've found that set up to work best, that way the cartridge alignments are set up correctly.
Here is some info that I didn;t know, until another member posted this inciteful explaination of why a dedicated mono cartridge makes a difference.
If your plan is to have a mono set up to play vintage mono LPs that were pressed between 1948 and ~ 1960 then you need a real mono cartridge with a spherical stylus. There are a lot of "mono" cartridges out there that are nothing more than a stereo cartridge that is wired for mono, and that simply will not do. They will work, but you will be no better off than you are with playing a mono LP with a stereo cartridge.

On vintage mono records the grooves are wider than they are on stereo LPs. They are also U shaped rather than V shaped. A geniune mono cart has no vertical compliance. The stylus only moves in the horizontal plane. Thus, using a mono cartridge on these LPs will yield better sound and less noise. The Grado you referenced is a stereo cartridge using a modern elliptical stylus with the generator wired for mono. This would not be an ideal cartridge to use for playing back vintage mono LPs.

If your goal is really to play mono audiophile reissues pressed on 180g or 200g vinyl then do not waste your time and money on a mono cartridge. To my knowledge all LPs pressed today are cut on modern stereo cutting heads. No one is making mono LPs with U shaped grooves. Using a spherical stylus on these records will wear them out prematurely and they will not sound as good on a mono cart as they would with a modern stereo cartridge.

The only genuine mono cartridges that I know of besides the classic Ortofons is the Shelter 501 mono and the Miyajima Labs Premium Ebony mono. There may be others, but these were the carts that I found.
"A genuine mono cart has no vertical compliance."

I've seen that written in many places, but it's difficult for me to even conceive of a cartridge with absolutely no vertical compliance. How does it deal with warps? It seems even the slightest surface irregularity would send the whole tonearm flying up off the record if the cart has no vertical compliance. Doesn't there have to be at least some degree of "shock absorption"? Can someone fill me in?
"The only genuine mono cartridges that I know of besides the classic Ortofons is the Shelter 501 mono and the Miyajima Labs Premium Ebony mono. There may be others, but these were the carts that I found."

Benz, Lyra, Koetsu all make genuine mono carts. All made to order.
Some general information about "modern" Mono Cartridges I used or listened to.
In a way I prefer those from Lyra based on their Design principles ( but a Shelter 501 mono sounds also very good). Lyra mono cartridges use a vertical coil which is only capable of detecting horizontal stylus movements (corresponding to mono groove modulation), and they have TWO identical mono coils to avoid the possibility of ground loops with stereo phono stages or preamps. For me, it is a step ahead ( I had with a cheap Dorian Mono better results than with much more expensive 'mono' carts from other Importers...) . Other cartridge manufacturers may use different methods, like using stereo coils and summing the outputs to derive a mono signal, but in my experience this way is no better than using the "Mono" button on a preamp, and will be limited by how well the two stereo channels match (crosstalk, phase, frequency response, output balance etc.). Generally, my experience here was not positive. Too mediocre. But cheap. For some this is a priority.
Another discussion is the time era from these Records, of course there are differences, but to keep the story simple, I use late 50's ++. I don't think that the differences between the original LPs and modern reissues means that much
for cartridge or stylus design. The commonly voiced concern with "wider mono grooves" has no meaning, in my experience. The most important thing is that the LP groove continues to have a 90-degree cross-section. Older LPs have shallower (and dirtier) groove bottoms, so a stylus that reaches particularly deeply into the groove may cause problems. In my experience, a line-contact stylus with a smaller major radius like 30um may cause problems with older LPs (and this is same for both stereo and mono records), and so for older LPs I would recommend a cartridge that has a somewhat larger major radius 70um, but it is not a general rule. Depends how fanatic you are, in what condition your records are and of course, what kind of Quality your Playback System has. The Lyra Mono have interestingly a different kind of Sound than their Stereo "brothers", more "juicy" with a greater sense of immediacy and presence. Has to do with the two coils, even when the output is only 50% from them...
Summary: Based on the superior tonal colors in the old mono records, much a much better low register the Mono Trip can be really interesting for the discriminated Listener.