The m-disc DVDs are quite different from the blurays, so it depends.

Here is a test of some m-discs on the latest Pioneer drive:
https://www.cdrinfo.pl/artykuly/artykul-Pione … sh/strona11.php

Also check out the single sentence in the 'summary' on the last page(20) there, about m-discs.

About the M-blurays... maybe not worth it, compared to say good old Panasonic bluray discs (?):
http://goughlui.com/2015/10/16/review-tested- … c-4x-bd-r-25gb/

As for longevity, which really is the only point of interest here, I sadly have absolutely no idea... Though the special DVDs might be 'interesting'... 😀

From what I undestand the write medium is almost rock-like..
I've never used one though my writer is supposedly M disk capable.
I guess it lends a whole new meaning to the phrase "written in stone"..
if the hype is to be believed..then the data on this written only once medium will indeed last a lifetime (claims of 100 to 150 years).
..but since no one can see into the future..how realistic is a claim that has not and cannot be verified...yet.
The only durable disc medium I can only claim I have verified is PD (phase differrential) at least in the medium term.
Is data I wrote to PD discs back in the days of win 98 ..so 20 years -ish is still 100% intact on a recent check I made.

I have tons of CDR burned in the 90's that still work fine (think they used better media back then). Phase change media that needs heat (Magnetic optical) should last a long time but that kind of died out (too bad since the cases seem indestructable).

The problem I see with long-term data storage on any kind of media will be the ability to read that media far into the future...not from decay, but from the simple lack of working drives with which to read them.

M-Discs are SUPPOSEDLY rated to last up to 1000 years in storage (Yes, one thousand). Let's be more realistic though, and just go ahead 100 years. Can you guarantee with absolute certainty that there will still exist functional optical drives in 2118 that can read M-Discs burned in 2018? Or, at the very least, that the Average Joe will have immediate access to the very few that may still exist in museums? The discs themselves may be perfectly fine and all of the data on them 100% intact, but if you have no means to read that data off, they're worthless.

Honestly, the best thing to do every 10 or so years is to refresh your backup/archival media. Keep up with the technology, transfer it to newer storage methods as they come around, rather than stick to the notion that the same data storage technology is gonna exist and always be readily accessible en masse for 100+ years.

Most people want to archive things they can still read before they die. 100-1000 years life is a great way to sell something that will still be usable in the lifetime of the owner. Nobody really cares about my pictures and files after I die.

Rolling archives is what most people end up doing. A decade ago I dumped 100+ QIC80 tapes to CDR and newer tapes (you need much less tapes thanks to technology).