That's the right way to test it for sure. And that should be the fastest drive in the 2TB I believe.
Apple states "up to" 3.2GB/s for reads and "up to" 2.2GB/s for writes, based on:
Testing conducted by Apple in June 2018 using preproduction 2.3GHz quad-core Intel Core i5-based 13-inch MacBook Pro systems with 8GB of RAM and 1TB SSD, and preproduction 2.6GHz 6-core Intel Core i7-based 15-inch MacBook Pro systems with 16GB of RAM and 1TB SSD. Tested with FIO 3.7, 1024KB request size, 150GB test file and IO depth=8. Performance tests are conducted using specific computer systems and reflect the approximate performance of MacBook Pro.
So it looks like you're ahead on the writes and behind on the reads. But maybe you can adjust the Black Magic settings and see how it compares to Apple's not above.
I'm sure others will chime in with their results and you can compare.