Fact:
The trait that you wish to avoid passing on is the PROPENSITY to herm under only moderately stressful conditions.

I do not like to force-herm because a) I have mother plants coming out my EARS and all the female clones I will ever need and b) I keep several excellent males for breeding purposes.
I would only force-herm in an instance where I was down to a single remaining female of a line and had no other way to preserve her genetic material in case the unthinkable should happen. In this case, photoperiod is my preferred method. I'm a chemist. I run a chem lab, and I fuck around with toxins, carcinogens, mutagens, endocrine disruptors, and plain ol' irritants on the daily; I've got the safety training and equipment to do it safely (fume hoods and ppe), I can dispose of waste according to EPA regulations, and I STILL don't like the idea of even MYSELF fucking around with that junk at mi casa.

As for weakening the line by breeding with herms:
NEVER breed with a natural herm.
IN EMERGENCIES breed with a herm that popped up in a known-stressed garden.
ALWAYS force-herm a few females and preferentially save the seeds from the female that you found most difficult to force into pollen production.

Your goal is to ensure that under even slightly stressful grow conditions your resultant females will not go herm on ya. So your secondary goal in force-herming a plant is to stress-test it into telling you whether it has a strong propensity to herm.

Fact:
You can use photoperiod, high temps (raise the top of the plant right up into the light so it shows acute heat stress), or over-ripeness to naturally force herms. Nanners should show a couple weeks after the expected harvest date.