But let me phrase it a bit differently than I did before. First off, I probably need to own more than a few mono LPs before I'll consider the trouble and expense of a mono cartridge. Otherwise hopefully I'll have a mono switch on my pre or phono amp and be content.
However if I've purchased many mono reissues, better optimization may be worthwhile. If those reissues were cut since maybe 1990, they very likely were done with a stereo cutter head. So choosing an appropriate stylus suggests a modern profile, whether it is in an "adapted" stereo model or a true mono design.
But then if I own a number of original mono pressings, produced with mono cutter heads, my stylus choice will likely be different. Why would I not want a larger, conical/spherical stylus to better match the groove made by that cutter? Also in this case I do not want any vertical pick up so that affects my choice as well.
Without beating this into the ground I feel it depends on how many monos and how they were produced that we want to listen to.