sorry MAriner but you are wrong. The water content is a direct result of the filtration method and is independent of the gas. Nitrogen does not hold more or less water than air. If you filter both gasses through the same stack the end result will be the same water content.
I run several gas blending stations in the UK and abroad and they are subject to rigorous testing. We also use Nitrogen, Helium, Oxygen as binary gasses for blending as well as plant supplied air for comparison testing and I can assure you that in the realm of commercial gas which we are discussing her the water content is the same.