2013 Mac Pro: 1TB SSD Faster on Writes
Just tested— the 1TB flash storage (SSD) option in the 2013 Mac Pro is a big bump up in write speed over the 256GB and 512GB SSDs.
Observe a write speed of ~929 MB/sec vs ~755 MB/sec for the lower capacity options. I can’t rule out OS X 10.9.1 vs 10.9.2, but OWC tells me that this difference is their same observation.