regarding the speed discussion, based on the comments, I guess the purpose and functionality of Thunderbolt is not fully understood. Thunderbolt is not a competing I/F to eSATA, USB3 and others.
Thunderbolt is just a encapsulation of display-port and the PCIe Bus for your PC or Mac, this means it can only drive a display-port Monitor directly, without any chips, the important 2nd part of Thunderbolt is the encapsulated PCIe bus, this means one or many PCIe cards or chip sets can be in a external box of your PC or laptop (in this box can be additional multiple SATA I/F, display cards(with some limitations) USB3 controllers etc). If you connect to a external HD with Thunderbolt, then the external box has a PCIe SATA chip set to connect the disk, this means a disk connected directly via eSATA to PC will always be faster, because there is no overhead for the Thunderbolt protocol to encapsulate the PCIe bus. But on the other hand, you can have multiple PCIe cards or chip sets in the external box and then reach via a single cable transfer rates of up to 2x 10Gbs, combined for all I/F in this external box. To have faster disk access, you will need to have Fiber Channel controller in the external Thunderbolt box, but same as before, the Fiber Channel controller in the server itself will be faster.
For a desktop or server PC means this, connect your disks to eSATA ports or internal PCIe cards for maximum speed, but if your PC does not have any free PCIe slots anymore (and a laptop at normal does not have any PCIe slots), you can add now multiple PCIe cards/chip sets external. For a laptop it means you can connect like a docking station multiple high speed devices via only one Thunderbolt cable. There is definitely NO speed advantage when using Thunderbolt for a single native I/F.
To get the understanding what overhead is needed by Thunderbolt for the PCIe encapsulation see now the speed measurement of same Samsung 830 series 512Gb SSD when installed as main disk in MBP (SATA 3 I/F), just for info, the SATA controller in the Seagate Thunderbolt adapter is also a SATA 3 controller.
Samsung 830 as internal boot drive in MBP (filesystem is HFS+)
Samsung 830 installed in Seagate TB adapter (filesystem is HFS+)
So you can see you loose about 20% performance via Thunderbolt. When now the internal speed test from Black Magic is now compared to HD Tune values for Samsung 830 512GB, then the ratio for comparison should be approximate clear.
Hope this helps, for what applications Thunderbolt can be used, or not. (regarding HD speed test in VM's, HD Tune, ATTO and others when used in VM's, seem to show wrong results (a lot to high values, higher then the native speed) this needs further investigation how to make proper speed measurements (seems all disk I/O is buffered), so only real files copied can be used)