In general it is the total "writes" or "total bytes written" that determine SSD lifespan...some brands have a much higher rating for MTBF on "bytes written".
Right... But a couple of things:
First, while longevity is acceptable, the
way it dies is nearly always catastrophic. While mechanical drives may fail in a catastrophic fashion, they don't have to, and tend not to... If I can get the thing to show in BIOS, I will likely be able to recover something - and even without BIOS, though that is becoming very limited. Usually, if a mechanical drive is wearing out, you'll get some lost sectors, or the part will suddenly die... But you can see it coming... With time to save or recover data.
That is generally not true with flash based drives. They just DIE... So all data should be treated as volatile at all times. And in the end, there is only one fix for that, which is, as always, replication. The need for excellent backup has only increased.
And my second thought... varied degrees of durability has always been the case - Even in mechanical drives. And that also is only getting worse. Shoot, I still have Quantum drives laying around that work just fine... And Quantum was bought out by Seagate how long ago? You will find it a hard go to get that kind of durability today... In fact, I have not trusted much of any of my old go-to brands for quite some time, and only rely on WD Black nowadays... And until that proves untrue, which it eventually will, I will abstain from the race to keep on top of whose drives suck - because mostly they all do.
But it is the same thing in Flash based drives - You'll likely be ok for a while with any of them, but there is some benefit to named brands - I pretty much stay in Crucial, Kingston, and believe it or not, PNY.
But even without writes - I am getting older SSD drives to my bench that were only used for offline storage, kept in a dark drawer, and years later attempted access was made unsuccessfully. Certainly well within the write limit, these drives have somehow degraded and have become defunct simply due to age (to the best of my reckoning).
... Which is why I don't really trust them long term. My only solution so far is to keep my whole data pile live and replicated multiple times.