Not to discount your point about retail availability, but this appears to use the M.2 (NGFF) format, which has been widely praised (outside of any Apple context) as an industry-standard approach to flash memory.
http://www.anandtech.com/show/6293/ngff-ssds-putting-an-end-...
The M.2 form-factor is available for both SATA and PCIe cards. PCIe versions are becoming the new normal, due to the speed increases - http://www.tested.com/tech/pcs/456464-why-ssds-are-transitio...
