We have performance comparison information on our web site. Check the performance tab on Tempo SSD or Tempo SSD Pro product page. This will give you a pretty good idea.
These numbers can be generalized. For one SSD you can infer from the table.
Read speed over Thunderbolt = 90% of rated read speed in a Mac Pro
Write speed over Thunderbolt = 80% of rated write speed in a Mac Pro.
Go to the manufacturer's SSD product page, check the speed rating and multiply by 90% and 80% for read and write, respectively, for performance over Thunderbolt.
For two SSDs in a RAID 0 in the Tempo SSD Pro using the original Thunderbolt 1 bandwidth limit, the speeds get capped at about 700MB/sec read and 560MB/sec write. There is no bandwidth limit for a two-SSD RAID 0 under Thunderbolt 2 or Thunderbolt 3.
