OWC Thunderbolt 3 Dock: SD Card Slot Speed vs Dedicated Card Reader, 2015 MacBook Pro
See also Thunderbolt 3 and USB-C Infographic and OWC Now Has Thunderbolt 3 Cables.
The about $299 OWC Thunderbolt 3 Dock has among its other ports a front-facing SD card slot (very handy compared to the anti-design of the rear slot on the iMac 5K).
Attached to the 2016 MacBook Pro, I wondered how the SD slot would fare versus the card slot on the 2015 MacBook Pro (my travel laptop), and how both would fare versus a dedicated high-speed SDXC card reader, the Lexar Professional USB 3.0 Dual-Slot Reader UDMA 7.
Of course most users shooting JPEG just won’t care about speed much, since 90 MB/sec is quite fast and JPEGs (even 50 megapixel JPEGs) are not all that large. For that matter, most users won’t be using a pro-grade card even 1/3 as fast as the Lexar Professional 2000X 64GB SDXC.
But as a professional photographer, when I am shooting huge raw files and a day’s shoot is 30GB or more, I do care, especially after hiking back from a grueling dawn to dusk outing and I haven’t eaten and want to get some shuteye. Ditto for any photographer on a time-sensitive deadline.
A dedicated card reader supporting the special UDMA modes rocks—bottom line for those for whom speed matters to an SD card, the Lexar Professional USB 3.0 Dual-Slot Reader UDMA 7 'rocks', whether plugged into the OWC Thunderbolt 3 Dock or a Mac Pro. The bundled Lexar SD-only reader is fastest of all, but it doesn’t slot in next to another USB device, so I tend not to use it.
Tested using the read-files command of diglloydTools DiskTester.