I think humble is asking about using feminized seeds to breed with. While there doesn't seem to be a definitive answer from my research, some have claimed to have normal results when breeding a feminized seed with a male. The long term effects are unknown however. I have heard from breeders to never use feminised seeds to breed with. Something about missing alleles. It's also said to dilute the gene pool if the cross is put out to the public to further perpetuate the genetic defects, if any.
Bottom line to me, with so much controversy on the topic, better safe than sorry. Use regular seed stock to breed with, IMO.