Samsung exceeds their claim of 300 MB/s read speed, but only with USB-C
Mac OS Extended (USB-C)
AJA
Read: 67 MB/s (25 MB/s USB-A)
Write: 316 MB/s (42 MB/s USB-A)
Blackmagic Disk Speed Test
Read: 68 MB/S (23 MB/s USB-A)
Write: 317 MB/s (44 MB/s USB-A)
ExFAT (USB-C)
AJA
Read: 62 MB/s (24MB/s USB-A)
Write: 314 MB/s (42 MB/s USB-A)
Blackmagic Disk Speed Test
Read: 66 MB/s (24 MB/s USB-A)
Write: 316 MB/s (43 MB/s USB-A)
macOS Mojave 10.14.6 Beta 18G29g
iMac Pro 2017
3.2 GHz Intel Xeon W
32 GB 2.6 GHz DDR4
Radeon Pro Vega 56 with 8 GB