It's not clear to me that there's anything special about the BDR M-Discs vs. other BDR discs.
It looked like original DVD M-Discs have been discontinued, last time I checked. IIRC, those where the things that all the articles about M-Disc longevity were written about.
(In particular, I think there was an article on HN a few weeks ago that did tests with both M-Disc BluRays and another brand. The M-Disc wasn't magic but it was a decisive winner.)
That's interesting. However I still have a couple questions:
1. My understanding there are significant brand-to-brand quality differences with optical disks. A better comparison might be Verbatim regular BDR vs. Verbatim M-DISC BDR than TDK regular BDR vs. M-DISC.
2. That article is from 2016, and I wonder if it holds up. From what I've read about optical disks, even were the disc was manufactured can be significant within the same brand. IIRC, back then they might have been making them in Japan, and I don't think they do that anymore.
You might consider M-Discs, which are optical discs as large as 100 GB (BDXL) that you can burn yourself, and which should have the same longevity as a CD-ROM.
Of course, if CDs are working for you, this may not be a problem that needs to be solved. ;)