If you mean, Bayards are more difficult to find than Stylomines: Based on my 10 months-long observations on ebay, I`d say 50:50.
I hope your black one is in a nice condition
Apart from Bayards & Stylomines I only own a Méteóre with a divine broad stub nib.
I also had a tiny Matcher Colombes in blue cracked ice celluloid (trés magnifique!!), which I gave to a friend (I MUST make a photo of it !!)
… speaking of little known French brands!
I got most of the pens in february from a French seller who had a dozen on ebay, 1 week apart. At the time I was hoping to catch at least one.
To my surprise there was no serious bidding & I ended up with 5 pens (guess I`ve been lucky!)
It looks like we have a few things in common
You know that your posts on Bayard pens had a major influence on steering me towards those pens!
Maybe i should make a photo of one of my Bayards, lying on top of Mysterium Coniunctionis (did I get that right ?), sort of like a homage
I actually do have another Excelsior minus rings, clip & clip-cap - impossible to find ersatz, though.
I also find it impossible to tell the difference between the Excelsiors, Le 8, Le Superstyl & so forth ( Le Superluxe for example does have especially nice purple/red celluloid, is bigger than the others, also holds more ink but is curiously shorter uncapped than the Excelsiors!
As to the filling system of the Superstyl: Like all of my pens they`re lever fillers. I know that Bayard also produced Safeties, but during the 30ies and 40ies? I don`t know.
I did research the brand half a year ago & found one site which had more detailed informations. I`m very sorry that I did not find it again at short notice.
I also had a look at the French forum (using google transl., as my French is only rudimentary );
the French seem to prefer more teutonic brands, but someone there has a collection magnifique des Stylomines 303 (worth having a look!!)
Here`s another picture which I did a few months ago when I got my new camera (still new at FP photography - some of the nib`s tips are cut off), all lever-fillers (2nd from right: swapped nib with a Franklin-Christoph Cursive, as I didn`t need it on my Pocket 40 but wanted to use):