I don't think that SLC mode would be very useful to photographers. A lot of modern cameras have a fairly large internal buffer in order to guarantee burst shots at a certain speed. So the camera isn't going to shoot any faster potentially until that buffer is used up on the camera. At that point, you're probably not going to get much of an increase in performance with this SLC caching over just a fast microSD card with guaranteed speeds.

For video, this makes even less sense, because if this card is only fast enough for 4k video when the SLC caching is used, then it has a finite time for recording that is likely much lower than the camera or regular, fast cards would have.

I can only really see this SLC caching working with random read or write use cases, like using apps off of the card. I am interested in the fact that the cards have stated endurance ratings. That is fairly uncommon for these cards and again point at a card that is targeted at application or whole-OS usage.