I am in the process of replacing a 40 gallon electric water heater. Looking at a Rheem. They offer a 6 year ($409), 9 year ($549), 12 year ($739) and a variant called a lifetime water heater ($1100) that is lined with some type of plastic that prevents tank corrosion. I am trying to understand is this lifetime unit worth the extra cost. Any opinions on this? Would I still have anodes to replace in this plastic lined variant?