Hi- in an effort to help my mid 2011 27in iMac limp along until the new Pro's are released I've bought a Crucial MX300 520 Gb SSD and put it in a OWC Mercury Elite Pro Dual enclosure connected over Thunderbolt. This is a massive improvement over my old, likely failing 1 TB HHD, but I'm only getting read/write speeds of 300/320 Mbs via AJA. The MX300 is not the fastest SSD, but I was expecting speeds more in the 400 Mbs range. I've swapped cables and had the same result, and I've tried hooking the enclosure up to a 2012 Air and gotten the same results via TB, and somewhat faster writes over USB 3 (380 Mbs- same read speeds). So, my questions are... 1) Is this really all I can expect from the drive given it's speed? 2) Is TB slower on the mid 2011 since it was one of the 1st to have the connection? 3) Is the OWC enclosure holding the drive back? I saw it's really only rated to about 450 Mbs, but I'm not evens seeing that. If it matters, I do have the enclosure in port 1 (which provided a bump in write speed over port 2), and I have a 1680 x 1050 LCD on port 2. The SSD is about 44% full. I have the enclosure set up in JBOD mode with a 7200 1.5 TB drive in the second spot that I'm using for backups. I got this open box for about $190, so it's pretty much the cheapest thing I could get. Other than the speeds I'm pretty happy with the flexibility, and it is faster than my older FW 800. I've not had any trouble with it so far. I bought it to avoid having to open my iMac and install it internally, and I'd still prefer to avoid that.