A prominent HT doctor recommends using transplanted nape hair at the hair line to soften the look of the hair transplant and make it look more natural. This seems to make sense as often hair transplants look like the hair strands are too thick where transplanted and not natural. You mentioned that nape hair is not permament. Does this mean it might fall out over time and even if it does is it still worth it for the cosmetic effect in creating a more natural hairline?
I recently saw a patient in my office who asked me this same question and asked about the doctor. In case you are the same person, my answer was as you correctly state — nape of the neck hairs are not permanent. Some patients actually come to have hair transplants to the nape of the neck, as they are completely bald from below the ear level.
Thus, your nape of the neck hairs that are transplanted elsewhere may fall out over time and it is not worth the surgery. More importantly, even with the FUE technique there will be scarring that may show at the neck with white pale dots if the nape hair falls out over time. If you are considering this type of surgery I would ask that doctor if you can meet with a patient who has had it done to see what it looks like. When the donor area is from the nape of the neck with strip surgery, most of the time the scars are prominent and wide. Scars like these are not amenable to repairs and even with FUEs placed into them, they can not really look normal.
If you want a softer hairline, regular donor hair should be sufficient if done right with single follicles that are finer and grow naturally that way. If the staff and the doctor are good, they will pick out the smaller caliber single follicles for the very front.