Using copper pans as a shower base to tile over is a hot topic debated a lot in current days. The north east is the last stand for copper pans. A lot of contractors swear by them and won’t touch anything else. I am not a plumber but I have seen copper pans removed from old Victorians in Cambridge and they held back water for the last 100 years. A plumber that installed copper shower pans for over 40 years told me the drain connection in a copper pan is the most reliable since we solder the brass strainer to the copper base. Other pans like rubber use compression fittings that use a rubber gasket to hold back water. I don’t know what type you would want holding back water over your $30,000 dollar kitchen renovation, but I know I would prefer a metal that has been tested throughout time and is trusted by many old time plumbers that have seen it all. That being said, yes, copper shower pans are quite a bit more money then anything else but that is because copper is such a high demand metal and the cost is always fluctuating. We have been making copper pans for the last 20 years and our pans have never leaked once. Knock on wood. If you are willing to get what you pay for I encourage you to think about copper being your extra insurance for a good night sleep and worry free renovation. There are lots of areas in life to save money and cut corners, Water damage is not one of them. Copper is the way to go.