Why would I not buy 2x Samsung 256?
Well, performance wise a RAID0 of two Samsungs 256GB would be better than RAID0 of two Crucial MX100 @ 256GB because only the 512GB has almost-capped SATA/600 write performance. The 256 and especially 128GB versions of the MX100 are quite a bit lagging in this area. Something to be fixed with MX200 with its dynamic write.
But regardless of performance, i have some concerns about the software protection used in Samsung SSDs when it concerns anything other than regular desktop usage. This has to do with the feature that reverts the SSD to an earlier state. For desktop this is not a problem at all. But what if some SSDs in a RAID0 array revert, while others don't? Then you have a filesystem spanned across all SSDs with parts new and parts old data. Probably all you'll see is some filesystem check when you boot. But this can really hurt things potentially as the filessytem is only designed to cope with lost recent writes AFTER a flush request. The flush request (FLUSH CACHE in ATA-terminology) is holy to maintain integrity, and Samsung SSDs do not honor it.
When everything reverts, so does the metadata. The result will reflect a filesystem that is consistent (i.e. the metadata matches the stored data). Perhaps lost recent writes but the 64MiB journal takes care of that.
But if parts revert, your filesystem will experience a condition where parts of the metadata may not match the data, and parts of the metadata may not even match other metadata. This could be deadly if you have important things stored. Though i guess the filesystem check will do its work.
So what could be the result? Well, it could mean Windows won't boot anymore, for example, and you get some blue screen when booting. But people will think oh its power supply oh its the BIOS oh its the videocard, etc. A reinstall and it works again. Hmm maybe it was the driver i installed last week, yes that could be it! I can cry about these kind of things, which i regularly see on the Dutch techforums that i roam.
Again, the Crucial drive is the best option for most consumers, but why stretch these comparisons?
Well i consider them both excellent SSDs for desktop usage. But the Crucial MX100 is quite a bit (20%) cheaper than Samsung EVO, which is a TLC SSD. And the Crucial is slightly better in my opinion thanks to its hardware protection. But i agree the quality difference for desktop users is negligible. But the 20% price difference is hard to deny, unless the difference is much smaller in the US?