Plextor M6S & M6M (256GB) Review

Final Words

The M6S and M6M are mostly marginal updates to their M5 series counterparts. I believe Plextor's number one goal with the M6S and M6M was to cut costs by utilizing a cheaper controller and smaller lithography NAND and that's why the performance improvements are only minor. It seems that most, if not all, SSD OEMs are preparing for the PCIe era and all the updates we've seen lately have been rather modest with no firmware overhauls to significantly improve performance.

The IO consistency is the biggest issue I have with the M6S and M6M. While I understand that the lighter controller introduces some obstacles in all performance segments, the IO consistency seems to be built deep into Plextor's firmware because the behavior has been the same with all Plextor drives I've tested (even with the M6e). For a light user I don't believe that is a major issue as long as the user keeps ~10-15% of the drive empty, but truth to be told there are other mainstream drives that have far more consistent performance (such as Samsung SSD 840 EVO and Crucial M550).

Another thing the M6S and M6M miss is hardware encryption support and more specifically support for TCG Opal 2.0 and IEEE-1667. There is AES-256 support but only through an ATA password, which isn't the most secure and requires BIOS support to function. Especially for laptop users that can be a deal breaker since laptops are much more vulnerable to theft, and personally I wouldn't use a laptop for any work purposes without some form of encryption. 

The MSRPs seem very, very high for a mainstream drive. Plextor's MSRPs have been quite over the top in the past as well and I would expect pricing to drop to M5S levels, but even then the question is: are the M6S and M6M price competitive enough? The 250GB 840 EVO can be had for $50 less than the 256GB M5S, which is substantial considering that the EVO has better performance and support for hardware encryption. Crucial's M500/M550 are alternatives as well with affordable pricing and especially the M500 is unbeatable for value oriented buyers.

Update 4/17: Plextor just sent us updated MSRP pricing, which I've listed in the table above. The changes are rather significant as for example the 512GB M6S drops from $500 to $400, making the pricing much more sensible. The M6S is now close to the M550 and 840 EVO in terms of pricing, although if I had to choose, I'd still go with the M550 or 840 EVO due to better performance and feature set. 

All in all, I think it's currently very hard for the tier-two OEMs (i.e. ones without a NAND fab) to compete in the mainstream SSD market. Crucial and Samsung are dominating the market with very aggressive pricing and competitive feature sets. That said, the M6S/M6M can be a decent buy if the prices drop enough, but I find that unlikely to occur due to Crucial's and Samsung's NAND advantage. With better performance and an improved feature set the M6S and M6M could be more competitive, but as it stands there are better options in the market, namely the 840 EVO and M500/M550.