There are pros and cons to using a non-Lego surface. Pros are that you have more realism, more flexibility with moving figures, more interesting and unique terrain, and it looks cool. Cons are the huge mess, the more complex balancing, and it's not as simple and easy as base-plates.

I don't have any experience with it, but I'd say to give it a shot. Just because others may or may not like it doesn't mean you have to follow them. I think it's a cool look, and if you like it, then experiment with it! That being said, I'm old-school, so I haven't, and probably won't, depart from the good ole baseplate look.

So, in short, get some kinetic sand and try it yourself!

That being said, off the top of my head, I though Brotherhood Workshop used more clay than kinetic sand. I may be wrong, it wouldn't be the first time.

He has so far just used kinetic sand in these   two videos

I have also been thinking of getting kinetic sand, as there are quite a few brickfilms I would like to do that take place in a desert, and I can't really see any problems with it at the moment, so I would say go ahead! Just beware that if you find yourself needing to bury something in the sand and it is not completely smooth (e.g. a minifigure) then some bits of sand may come off of the main layer and go on the minifigure (but it will probably come off in big enough chunks so that it won't be too hard to get it off).