[BroadHopper]

The Marathon Heater may be made of plastic but it's weakest link is the metal connector to the house plumbing, it tends to corrode and need replacement. Why don't you look at the tankless heaters, you will save more money on the long run. You may be able to get an energy rebate to help pay for the additional cost.

If your 1950 water heater is still good, chances are you must be using lake water, its softness tends to be gentle on the pipes.