I'm making a comic version of my published book and I've been using for years, nearly exclusively, V4/M4 for all of my artwork.
As such, I have a plethora of accessories that are affiliated with those characters exclusively and in fact, aren't available for Genesis..

I'm obviously impressed with the design advancements of the Genesis series but I have no desire what so ever of trying to convert or replace all my Poser V4/M4 assets to accommodate the Genesis line so while I'm desirous of using the Genesis line I'm only mildly disappointed in the design flaws of the Poser, V4/M4 characters and I can live with that.

Now I see all the new hoopla on the La Femme/L'Homme build but no actual educational info on why I should consider buying into the series and abandoning the old V4/M4 series.

Can anyone spare the time to explain not so much why the characters are better than V4/M4 as what benefits I will get from using the characters rather than the V4/M4

Maybe not the expansive response you might be hoping for, but you don't have to stop using your V4/M4 in Poser unless you want to. There is no requirement to exclude your previously installed content. It still works fine.

Ok.

I wasn't planning to stop using my V4/M4 unless the La Femme series offered something better that could still utilize my vast collection of accessories.
That's what this thread is asking for.
A reason that fits my needs to switch.

As parkdalegardener said, you don't have to abandon V4. I use both, along with many other figures. I do images for my own book series so I need a lot of characters. And while I can use a ton of morphs for V4, I find after a while, they start to look a bit alike. Adding another figure helps avoid that. I find La femme easier to pose than Vicky. She's also lower poly which means easier on the memory needed when I want more than a few figures in a scene. At this point, I wouldn't go back and change any of my characters to use her instead of the original figure, even if I could get her to look like them because it would mean a lot of work. But as I create new figures, I'm quick to load her, even if it means converting clothing. With the body handles, I find it easier to make expressions or tweak existing ones.

Some basics:

Bendiness and skin: natural joint-bends, realistic flexing of muscles, etc, said to be the equivalent of G8F. But if your V4 is not a half-naked contortionist, that many not matter too much.

Skin: Advanced skin, renders with SuperFly. But your key word here is "comic", so SuperFly won't matter if you're using the real time Comic Book options.

Face control: 30 face-control chips, to fine tune expressions. Although apparently the new face-rig means she can't take any legacy expressions. That could be a big drawback when making a comic with six expressions on each page, across 70 pages, and you can't use any of your vast V4 expressions library.

Talk: Works with Talk Designer.

Poses: Takes most M4/V4/A3 body poses. 

Hair: There are V4 skull morphs and V4 hair-fits.

Clothes: Much better range than at launch, but still limited. I've not heard of anything that's a solid "V4 to La Femme" auto converter for clothes, which would let you use "my vast collection of accessories" on La Femme.

If you want the technical details of the body there's a webinar on Youtube by the maker: https://www.youtube.com/watch?v=Q03FqB7rMow

Crossdresser converts V4 clothes to La Femme as long as you buy the La Femme license.

https://www.evilinnocence.com/crossdresser

Looks like the La Femme license is half price ($4.98) here at rendo now.

https://www.renderosity.com/rr/mod/bcs/la-femme-crossdresser-license/139469/

There is also the V4 Prefitter and the La Femme Morph for it along with Poser's Fitting Room that does a decent job of converting clothing.  In some cases, there will be little to no adjustment, just a straight-figure conversation to conform to the rigging.

You do NOT need a V4 license for crossdresser, only the target figure. Some clothing works well, some does not.

IMHO, LaF is as cute as Posette was. Downside, I can't figure how to craft a 'LaF_Lite', as the high poly-count and morphs etc make for a complex mesh and massive CR2....

FWIW, I'd missed that news of a LaF cross-dresser licence...

Oh ! Hadn't !! Says, 'PURCHASED' !! Hmmm...