I just got my new rMB, the 12 inch MacBook 1.2 Ghz 512 GB SSD. I only have 160 GB free. I know that SSDs can slow down when they are overly full. But I was expecting a bit faster SSD speeds, more in line with my iMac and previous MBP with the latest SSDs. I am only getting about 463 MB/s write and 800 MB/s read. Can anyone else with a relatively full SSD share their speed test?