as Dave says, as long as 16GB per slot doesn't exceed the mobo specs, you should be good.
as to dual vs single, the way I've always thought of it, although you will see a gain in dual and granted, it's not great, what you tend to notice is more things will be able to be running without the PC slowing down.
personally, I'd be putting in 2x8GB sticks.
not much difference in price, you will get a slight gain but if one fails - only one fails. all your eggs aren't in one basket.