Drive speeds ... PCIe vs external thunderbolt SSD I have a new 2014 MacBook Pro with 1TB internal PCIe SSD.
Blackmagic Disk Speed Test is reporting read/write speeds of over 900MB/s.

I am debating whether to swap this machine for a 512GB one (saving $500) and using an external Thunderbolt SSD drive, which would be cheaper and more practical.

My questions are:


Is that 900MB speed realistic? Seems incredibly fast.
Could an external Thunderbolt SSD be that fast? Theoretically Tb can do 10Gb/s ~ 1200 MB/s...
The 900MB speed is realistic, this is achieved on a few of apple's new mac offerings. 
An external Thunderbolt SSD would not be as fast, the only way to make it the same speed (or possibly faster) is if you have a multidrive thunderbolt enclosure running in something like Raid-0 with SSDs in all slots. 


The prior enclosure would be rather expensive though. It is probably best to have as much of that internal storage as possible as that is not easily upgradable. I would stay with the 1TB model more internal storage is always better.