Of course out/in...thanks Al ....Murphy's corollary of inversion... If anything can be inverted, it will unless you triple check.
Yes, mismatched Rce(sat) with Rjc differences as well causes causes Shockley effect and thermal runaway.
I have figured out these sensitivities and tolerances to guarantee "no runaway criteria " for power LEDs in parallel and how much Rs to add is sufficient for mismatched diodes. If thermal mismatch is less than electrical mismatch, it stable. The point of instability is a less than infinite time constant. The safety margin for aging must be at least -10-15 dB just like gain margin in op amps. Where the thermal/ESR ratio is the gain margin. Margin drops with the square of current peaks over design limit.or rise in ambient temp.
With this margin at worst case env, , Then long happy life.
Unless bombarded unequally by gamma rays ESD etc.or similar unknown disturbance
Also for fast CMOS, the protection must be faster than the device as discharge avalanche rise time is known to be 10 ps worst case, due to L/R which is beyond possible internal protection without added L, resulting in crystalline fatigue and rise in ESR.