The new control panel is installed, but not entirely finished. I will need to wait until it is a little warmer to fill the water tank and calibrate the water level sensor. But everything else seems to work well.
I had to enlarge the opening for the stock FWC control panel a little to make room for the back part of the switches, but this is entirely reversible. The switches left to right control:
1. The water pump - blue LED light is on when power is going to the pump and red run light is on when the pump motor is running. If the pump runs dry it is sometimes hard to hear that it is running, so the red led would let you know.
2. Water Heater - blue LED when water heater switch is on, red led comes on with ignition/relight just like on the Atwood switch. This was one of my motivations for this upgrade. We left the water heat on on several occasions because it was super hard to tell with the original switch which way was on/off and there was no indicator.
3. Inverter - blue LED when inverter is on and red LED for a fault (over current, low battery etc). My 300W Victron inverter is buried in a cabinet so you can't see the status LEDs on the unit itself.
4. Furnace - blue LED when furnace is on, red LED when thermostat is calling for heat. It is nice not to have fiddle for the tiny slide switch on the side of the thermostat itself.
The display shows battery voltage (redundant as I have a Victron BM-700 battery monitor as well), higher precision water remaining in gallons, and temperature of the water tank, which is useful in the winter.
I converted the hole from the original hot water heater switch (above left of control panel) to a blue seas 12v outlet (or USB charger). The panel is mounted in a somewhat awkward spot form the factory, but as the wiring and hole were already there, I kept it there. The only convenience it give is that it is easy to reach from bed.
My Victron battery monitor and MPPT control panel are in a more convenient location.