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.