I have to first admit that when I read your question I reviewed your previous posts.
The reason is because there is an experience factor that is important to the answer. You could run either, but what is the most appropriate for the job? You haven't mentioned that cost is an issue, which is typical when dealing with such a drastic difference between the materials. To most DIYers, this is important since the money is out of pocket.
Maybe you need to be more clear as to what your concerns are and why.
If you are a general contractor looking to save money by not calling a plumber, you could create a possible hazard to the customer and both will pay in the future for missing critical details.
I'm becoming less tolerant of general contractors who put the public at risk for a personal profit, so please don't interpret any questions as hostile. I just need to know where you stand before I give any advice.