And here's one for the OP to contemplate some.
Mead yeast ? Ok, so it's been what ? 150 years or there abouts since Pasteur understood yeasts pretty much in the same way as today.
Fine.
Then there's the fact that Meads, as most people think of them, were mainly drunk by the Vikings, Saxons, etc. The closest to them here (UK), was the Normans, who came from France and were already (apparently) into wines from further south.
Yes, there also seem to be some archaic recipes, that apparently date back to tudor times, though were the Tudors big on mead ? dunno, they probably drank anything with alcohol in it, which would have been wines, beers, ciders, etc etc.
Either way, given that peoples of those periods of history, didn't understand fermentation too well, and they don't seem to have had the faintest idea of yeast strains etc,
How in hells name do Wyeast and White Labs manage to find a "mead yeast" strain after what, a minimum of about 500 years ? I haven't heard of any samples of mead being found and analysed, otherwise there's be much greater choice of "mead yeasts"......
Hence as the historic recipes seem to suggest using beer yeast sludge, or mouldy bread or other source of yeast to ferment with, these so called "mead yeasts" are little more than over priced marketing bollocks. Sure, they do seem to work/do the job, but that's about it. No guarantee of historical accuracy etc, certainly no proof that they were ever used for mead making until White Labs and Wyeast started telling up that was what they were for.......
Personally, I'd go with some more recent guidance and suggestion(s).
If you read of Brother Adams (Buckfast Abbey, bee breeding mainly, but also he made meads) written stuff, where he mentions his mead making, he alludes to originally using "Maury" yeast. That became unavailable and he changed to using the Montpelier strain up to his death in the mid-90's.
Now "Maury" is a small AOC region/standard. It's entirely enclosed by the Roussillon AOC area. The only yeast I can find that seems to emanate from that region/area is D21. Whether that is the same strain, I don't know. It does seem to be good for making meads, particularly traditionals.
The Montpelier strain ? Well that's easier, both to find out about, as well as obtain in home brew packs. In the UK it would have most likely been packaged by Gervin, as their "Varietal E". But I believe that when "British Diamalt" when **** up, and the Gervin yeast part was bought by Muntons, it seems to have been dropped. Still not an issue though, as it's also the same under that name, as it is under another one we all know and will likely have heard of i.e. K1-V1116. Which is also good for meads, especially traditionals......coincidentally !
So there you go. 2 yeasts, with recent "form" for meadmaking, which while not really "genuine" mead yeasts, seem to be pretty damn good for meads........