There shouldn't be an issue with fem seeds as long as stable plants are used. I have grown many fems and have yet to find a hermie. Herm seeds are more likely to herm because the parent itself was a hermie, it's in it's genetics.I understood that herms are likely to make more herms in their seeds or using the pollen.
The same thing happens when STS is used to convert a female to a male. People do this with female clones trying to keep the strain / pheno and end up with bad seed.