The 850 Evo is no longer relevant since the MX300 delivers similar performance at a much lower price.
Isn't that overstating it a bit to say it's no longer relevant?
In 4k reads/writes with QD 1, the Crucial gets about 70% of the score reported by the 850 Evo in the benchmarks I've seen (and performed myself), and it typically costs about ~75% as much as the 850 Evo. For most users, this performance metric is more important than the others, and in it, the Samsung slightly outperforms its price premium, or at least holds its own (hard to state definitively, as prices bounce around so much).
The Samsung also has 2 more years of warranty (unless you exceed the lower TBW ceiling on the Samsung, which for most people is pretty unlikely) and has far better software. The Crucial Storage Executive can't do as much and requires Java to work, and has to use a browser for its UI. It takes an agonizingly long time to load even on a fast machine, while Samsung Magician is instant.
Even so, I came to the same conclusion you did, and I went with the Crucial for my laptop. Unfortunately, it just did not work with my laptop's ATA password function, no matter what I tried. Crucial support told me that the ATA password has nothing to do with the SED function, which directly contradicts what their own web site says, and he brushed off my attempts to make it work. A volunteer on their official forum was more helpful than the Crucial agent, but still the system refused to work with the ATA password set on the drive. It would not prompt for it at boot time; it would just hang up and then give an error message about the drive. I had to remove the password to get it to boot (even from a USB drive).
I returned it and bought the 850 Evo (which ended up being on sale for Black Friday for less than the Crucial), and it works perfectly fine with the ATA password, and the Magician software confirms that it is in encryption mode when so equipped. I know the weaknesses of this approach, but it's pretty good for protecting the data at rest.
Still, I imagine that most people won't even use the SED ability of either SSD, and even if they do, they still may not encounter this issue. If they are using OPAL or Microsoft eDrive to manage the SSD, the ATA password is irrelevant; it's not used. Even if it is used, it may work on other systems.
The Crucial is a good product, but not so good as to render the Samsung irrelevant.