There are no issues with SS. ...

There are no issues with SS. It is commonly used in the biopharm market as well as food and beverage for high purity water applications. I would however recommend using 316L Stainless for better corrosion resistance. That being said, SS offers no real benefits compared to CPVC or PVC unless the distribution piping is to be sanitized using hot water (80 C) or ozone. PVC if by far less expensive but if they are fabricating the system with their own product, the SS tubing will be at a much lower cost to them. Not to mention, they can use the system as a show piece for their products. One final thought, we typically only use CPVC instead of PVC in applications where the temperature will be elevated. Standard schedule 80 PVC will work just fine and reduce install costs. Hope this helps.