It'll be interesting to see what happens when I upgrade my y-bed to aluminum..., on the off chance that'll change thermal response in a way that triggers the default thermal runaway protection settings. Likewise when I eventually upgrade to a SSR for the bed.

Anyways, congrats on things working out!

As for the end-of-print z move behaviour..., hmm. Since I switched to the new firmware, I noticed that I tend to have a "z-positive" dimple (guess that's a pimple) at the pre-homing exit point. It's very small/minor. I can't honestly say I've been attentive enough to attribute it to any one thing..., i.e., I haven't noticed there's any Z movement at the end of a print at all..., but that doesn't there hasn't been.

I'll keep an eye out and report back. For the moment..., here is the tail-end of a typical print:

...
G1 X140.361 Y106.977 E2.63078
G1 X140.323 Y105.648 E2.65583
G1 E0.65583 F900.00000
G92 E0
M104 S0 ; turn off temperature
M106 S255 ; Turn on part cooling fan to help speed cool-down
G28 X0 ; home X axis
G28 Y0 ; home Y axis
M84 ; disable motors
M190 S0 ; wait for bed temperature to be reached