I know that these new Delkin CFAST Cards are not officially certified by BlackMagic Design to work with the URSA cameras, but I wanted to know to what extent it would work. I'm sure a lot of you shooting with the URSA want to know the same, so I'm throwing up this post. Without getting too technical or running any scientific tests, my experience is that it's probably stable when used at HD resolution (1080), lower framerates, and anything less than ProRes HQ.
So while it can work, I don't think it works well enough to consider this your primary storage. The super long delay of the DELKIN CFast Cards during formatting makes me a bit weary as well. If you're really hard up on a budget you can try those CFAST to SSD Adapters which give you best bang for the buck.
But those external SSD Adapters get in the way sometimes when you're trying to fly on a gimbal, or run a compact rig. Eventually you'll find you need at least one good set of CFAST Cards. At the moment the most reliable, 'officially supported', and least expensive CFAST Media for the URSA Mini is the Transcend Cards (found here).