Hmm..., think I have the answer.

Looks like it is a soft pwm...., a quick scan of the code doesn't reveal anything driving specialized pwm hardware. Freq is around 7hz..., I guess that, masked in with the other soft pwms (e.g., for the HE), that amounts to writing to a couple of ports a few times a second, without especially critical timing requirements. So, I'm guess'n it doesn't hurt performance much.

Cool.

I still think a PLA on blue tape test is worth doing, to see if it's worth going to any trouble in this regard at all.