I thought I would update this thread with my experience-
I connected my Radio Rx to the PPM input of the Navio. No problem. All working and with power.
I removed the Red + wires from all but one of the ESCs. Which I thought was the recommendation in the documentation.
As soon as I connected ESC #1 (the one with the + wire) the power to my Navio would drop out. But my ESCs were powered
I ended up removing the Red + wire from ESC #1 as well (so NONE of the Red + wires from ESCs were connected to Navio) and the power to my Navio stayed on and my ESCs were all powered. I have throttled up my drone successfully and all seems well.
The ESCs I am using are Multistar 20A Flashed with SimonK.