Here is a another sim. No matter the series R with Load C, even 100X load C,
I can't get it to osc. I can by increasing the darlington base C load, but as you can
see with .1 uF output still stable with an indication that phase margin is indeed
reduced. But load C, ESR, does not significantly impact loop.
Ignore the 1K ESR R, I used both .1 and 1 ohm in sims, no effect.
This sim switches full load on/off.
Regards, Dana.