What do contractors think of the new "hi-tech" drywall products?

I’ve been reading about new forms of drywall that are extra mold and moisture resistant, and other types that are extra sound resistant. Have any contractors worked with these yet? Do they merit the hype? Any brands you especially like? What’s the cost mark-up?

We use green board on our bathroom renovations. Its relatively cheap at $8.95 a board and we have not had any call backs yet so I presume its doing its job. There are also additives you can add to the paint to deter mold growth. Also, painting the bathroom in at least a satin finish is much needed.