My 64GB 300x model creates with Xbench on current MacBook Pro after all, up to 42MB / s uncached write (4K blocks) and an Xbench score of at least 45.92. In the overall performance and is thus, for example, significantly higher than the 64GB SDXC 600x of Komputerbay (Xbench score 33.83) and the very reasonable 64GB Savetch C10 UHS-1 (Xbench score 33.42). After 3h test shots with my brand new Lumix GH4 it seems even fast enough for their extremely demanding 200Mbps All-Intra mode to be - although the actually super fast UHS-1 U3 (= Class 3) requires cards (!) At least so far gabs no typo ... but that is subject to change.