There are two sources for 256GB SSD on our Retina 13". I, unfortunately, got the SanDisk one and my Write speed 550MB/s is 150MBs slower than what the Samsung one gets according to BlackMagic Design Disk Test. I would like to know what other SanDisk SSD MacBook Retina 13" owners are getting for their Write Speed. Is SanDisk SD0256F consistently 150MB/s slower than Samsung SM0256F counterpart? Here is a great benchmark that includes both drives and also other MacBook Pro SSD options (512, 1024, etc). http://www.harddrivebenchmark.net/ssd.html Appreciate any inputs, thank you!