IMO the problem with cotton is it absorbs. Unlike wool which wicks and stays reasonably dry, cotton soaks water up and retains it. That's the basis of the mantra "cotton kills". A cotton hammock would soak up any condensation and could turn into a soggy mess. While a breathable nylon would allow the vapor to pass through, cotton could soak it up.
That said, many of the hammocks used for full time sleeping are made of cotton and have a luxurious feel to them. I'm not familiar with a cotton/nylon mixture whether ripstop pattern or not. Something in my mind has an "ick" quality. But I'm more than willing to pass that off as my own gut reaction. If you have the cash to throw at an experiment... go for it. It sounds heavy but who knows. It might be worth it.