sudo trimforce enable
I've used the MX200 and it is much better than the BX100/200. The BX versions have TLC NAND flash and have very poor write speeds, even slower than many mechanical drives. The MX200 (500GB) or MX300 (525GB) are much better choices for a boot drive for OS X. Don't cost a huge amount more either. @Dramroun if you only need 250 GBs get the MX200 as the I/O is better than MX300 275GB. You can read about the BX SSDs performance on the Anandtech site.I'm using a previous model Crucial SSD in my MBP8,3 (M500, 960GB) and it works fine. The BX100 series is the entry level. I recommend the MX series for more robust speed.
Mine is a conventional Sata 2.5" SSD but I believe you can also get an mSata or M.2 version as well.is MX200 is sata or mSata ?