I am finally getting-a-round-2-it to install my Propex heater in my 1986 VW Vanagon Westphalia GL camper 2.1 L WBX auto.  I am leaning towards an installation under the back bench seat.  I am trying to understand the logic of removal of the built in rear heater, when some of the Propex installations are done.
Living in Canada, I find that I currently regularly use the vehicle rear heater for keeping the vehicle warm when driving, or getting back from hikes in the spring and fall to warm up.  I have never experienced any signs or symptoms of leakage in the rear heater valves or temperature regulation device.  I understand for those who do not regularly use the rear heater, or have it turned off, it tends to eventually leak.
So what are the pros and cons of leaving the rear heater connected, in an installation that has a Propex heater also installed under the rear bench seat?  I like the idea of some redundancy in having two heat sources.  I guess the main argument is the space that would be required for the Propex, and the decrease in storage space.  What other issues should I consider?
Cheers!Stuart