We are in the process of building a house and we're having two four ton Waterfurnace Geothermal units installed. The unit in the basement will be equipped with desuperheater. I am going to have a storage/buffer tank installed in series with a regular Rheem Marathon electric household water heater. What is the consensus on Marathon storage tanks assuming I can afford it? More importantly, does it make sense to buy the model that will not be energized or spend a few bucks more on the model that has backup electric element? Not sure about pros and cons. Also I noticed that the Marathon tanks come in 2 and 3 port models. How many ports would I need for my setup? Thanks in advance.