The camera is SDXC, but does not appear to offer U1 or U3. Even if it did, the DJI camera firmware has a bug (feature?) that locks the SD bus at "Normal Speed", which is 12.5MB/s.
Normal speed, 12.5MB/s is plenty fast enough for 4K and UHD video (60mbps encoding rate = 7.5MB/s), but really sucks when taking multiple (rapid shot or AEB in J+R) pictures and the camera locks up for 20-30 seconds while it writes the data to the SD card.