Whoo hoo! That sure sounds healthy!

Keep a bit of margin above the 1000 RPM idle, because to the best of my knowledge, below 1000 RPM the retardation curve ends and the timing falls back to "set angle" AKA 28 deg BTDC.

You won't notice much in a change in running behaviour, but the early ignition will hammer the rods a bit, and due to the low RPM there is not much hydrodynamic pressure in the big ends.

I have never tested to destruction so I can't say for sure if it will do harm, but my gutfeeling says to keep RPM above 1000 (I run between 1200 and 1400).
It also is pointless to go that low, the APC 18 x 6W allready becomes a very effective airbrake below 2K

But the stability of the idle shown, is exemplary! Kudos!