Personally I use the Komputerbay 3700X 256GB CFast from Amazon at $280. The Komputerbay can do 4.6K raw at 30fps, not sure about higher frame rates, and seem to have a higher write speed rating (495) than the ego disk (420).
The EgoDisk looks like they have better branding with slick packaging. I feel like I'm putting a 90s zip disk in my URSA with the Komputerbay cards.