Currently I have a 480Gb OWC Mucury Electra 3G in bay one of my SATA 2 sleds. I know that limits the SSD to 300MB/s, so I am weighing up the decision to buy a PCIE SSD card adaptor. If I get one, I want to get one that fits 2 SSDs for dual booting into Windows, which is about $140 for the Apricorn Velocity Duo. The trouble is the new m.2 cards are dropping in price all the time and have far greater performance, so it might be more worthwhile to hold off and go that route. I guess at this point it is a crystal ball question. Sorry.