Yep, I bought my wife the bandana version in Zion N.P. a couple of years ago during a heat wave.

They do absorb an amazing amount of moisture and they release it very slowly. They do feel very cool against the skin. The one downside is that they take time to absorb the water. They have to remain immersed for some time. The website says 10 minutes but I think it's more than that. When they do start to dry out you can't just dip them in a stream for a moment like a regular bandana. They have to soak in order to employ their full advantage over a plain bandana. And you'll need a container to dip them in. I would not drink water that they have been in contact with. The fabric is porous. But the good news is that they remain moist for a long time too.

Honestly, given the environment you'll be in and the shortage of water to hydrate these things, I'd personally go with a regular bandana. I'd rather drink the water. But they are great for car camping or areas where water is plentiful.