My URSA MINI 4K EF test results with the 256GB
EgoDisk, a steal at $280. Tried with the card formatted in camera as Mac OS Extended as well as ExAT.
4000x2160p60 Lossless RAW - Dropped frames after 2 seconds
4000x2160p60 3:1 RAW - No dropped frames (full card at 15:45)
4000x2160p60 4:1 RAW - No dropped frames (full card at 20:38)
Write: 260MB/s
Read: 426MB/s
(Blackmagic Speed Test v3.1)