I just took delivery of a 64GB Sony Tough card for use in my A7R3. I substituted it in Slot 1 for the 64GB ProGrade UHS-II SDXC formerly occupying that slot, and then moved the ProGrade card over to Slot 2 (knowing that slot can't take advantage of the card's speed due to the hardware limitations of the slot). Formatted both cards, and then shot some photos. I do not have any formal measurements, but my user experience was that the Tough card noticeably sped up the "write" process of the camera. It was definitely more than barely perceptible and that actually surprised me. I'd recommend the Tough card based on my experience (thus far).