This is not a comprehensive look at all the available cards that will work with 400Mbps ALL-I files, only the 128GB V90 cards sold by Panasonic and Angelbird. Both cards cost roughly $250.00 when I purchased them in Singapore a couple of months ago. To the best of my knowledge, the Panasonic retails for around $500 in North America, while the Angelbird has seen a price drop to $200 or so. My first Angelbird card failed on me, so I had to return it, which took almost exactly two weeks from the time I licked the postage stamp till the time the new one arrived at my door. The new one seemed to work. but I noticed it took much longer to copy the files to my hard drives than the Panasonic, so I decided to do a little experiment. I shot ten minutes of video (33GB) to both cards simultaneously and timed how long each one took to copy to a folder on my 2017 5K iMac. The Panasonic took 5 minutes 51 seconds, while the Angelbird took 6 minutes 2 seconds. Using Blackmagic’s Disk Speed Test, the Angelbird measured 55.7MB/s write and 82.4MB/s read speeds, whereas the Panasonic measured 75.3MB/s write and 89.2MB/s read speeds. For what it’s worth, V90 cards are required to be able to sustain a minimum 90MB/s sequential write speed. And while some may argue that V90 is overkill for the GH5, I don’t spend 250 dollars on an SD card for just the camera I’m using today; I expect it to work with any camera I might use in the future, including one that might shoot 8K or even RAW. So given the unreliability of the Angelbird as well as its inferior performance/price ratio, I cannot in good conscience recommend it. Many have also been using less expensive cards by companies like Adata, Sandisk and other manufacturers with success.
Edit: I have a hunch there’s a reason why Panasonic is recommending using V90 cards for the GH5, even though V60 should be enough. And I write cards with an ‘s’ for the simple reason that if you’re not writing to two cards, you’re risking data loss. My intuition tells me they’re trying to spare us purchasing two more expensive SD cards for the upcoming GH5s, which will undoubtedly require faster read and write speeds than even the GH5. Purchasing cards that are not rated V90 now is practicing false economy.