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.
Artmat55, unfortunately while mono playback seems like it should have simple answers it can be deep water. For example, beyond the basic question of mono switch (in phono stage or preamp or via Y-adapter as Lew mentioned) VS mono cartridge there are more areas to consider.

If one elects to try a "mono" cartridge, is it a true mono design or merely a stereo model with channels strapped internally? I don't see that being different from a mono switch on a preamp. True mono cartridges do not have vertical compliance pick up. This means they can reject vertical groove noise. For example I've read that Grado mono cartridges are strapped internally, but I've not seen a confirmation of that.

Then assuming you choose a mono cartridge, does it have the proper tip dimension for the records being played? Mono records have varying width grooves depending on when they were cut and pressed.

Lastly is the question of equalization. While the RIAA curve was formalized around 1956 not all record companies adopted it immediately. Some mono LPs (and 45s) released in the '60s were still recorded with other EQs.

So what is a music lover to do? I think it depends on how many mono records one owns (how much trouble is worthwhile) and are those monos originals or reissues (post about 1990)? This has been a long way of saying if the only monos you have are the reissue Beatles then utilizing your mono switch with a stereo cartridge can be satisfactory. Not that they might not be better optimized but are the sonic gains worth all that trouble?
A friend showed me what I thought was "conclusive" proof that his mono cartridge gave better results on mono recordings, so I bought a Miyajima Zero, which is very nice. But it seems to lack the ultimate refinement of my higher end Koetsu (stereo), on a selection of early mono vinyl.
With a lot of mono reissue (hence in RIAA eq), beside mono cartridge, will it be beneficial to use dedicated mono phono preamp? There is one offered by Oswald Mill at $1500 and rated A by Art Dudley, wondering if it can give significant sonic improvement on mono reissue.
I ended up buying a ortofon mono 2m and hear a big differnce! Thanks for the advice, I now look for momo vinyl in the shops! Just picked up Miles Davis 'round midnite!
Gondo, A mono phono stage adds yet another layer of complication, in terms of decision making. First, why use a mono phono stage if your "mono" cartridge is naught but a stereo cartridge that is internally strapped to produce a mono signal? In that case, one's "stereo" phono stage is merely processing the very same signal to produce two mono output signals, to drive two speakers in mono. I actually like that, because it produces a bigger more room-filling sound than I can achieve driving only one speaker of a stereo pair. Now, what might be the advantage of a mono phono stage? I guess it would be that the two stereo channels in your stereo phono stage are not exactly matched, thus producing subtly variant signals that end up as two slightly different signals on your two speakers, maybe robbing some ultimate fidelity. But if you worry about that, then why couldn't one simply abrogate the output of one channel of a stereo phono stage and thereby use only one half of it, to drive one speaker?
Do OMA suggest driving two speakers with the mono output of their mono phono stage, or just one? Probably the latter.

One could write several more paragraphs on the other things to consider, like for true vintage mono LPs not equalized for RIAA standards. In that case, if the OMA product has selectable equalization curves, therein would lie an added value. But it's a sticky wicket.