This one is simple: don’t do it.
The idea of putting any face onto a 3d model seems very appealing. How hard can it be to take a picture and apply it to a face model? Sure, there is some shaping to do, and the face tools claim to do this. Headshop 13 uses both a frontal and profile picture to do this. Neither Face Transfer nor Headshop do this very well. In real life our skin is mostly uniform across our face with allowance for stubble and eye redness/bags. Both Headshop and Face Transfer creating textures that vary wildly based on the light. Places where shadows fall become darker. This really just means your face to model utility only works from the same angle your picture was taken. And eyelashes. Any eyelashes will become part of the face texture. None of these utilities can see around the eyelashes to fill in the skin underneath with skin tones. So your textures are useless for anything but very low res video game models. This is the real deal breaker. To make the most of one of these tools, you need to doctor the photograph first to remove eyelashes and their shadows. Or use the face to model tool to create the shape then use another skin builder/editor to make a new skin for the model. And then we get to the rest of the body. Headshop just ignores this. The body texture will be whatever you started with. Face Transfer tries to extrapolate the tone of the face to create a body material.
Between Headshop and Face Transfer, Face Transfer wins. But the comparison is between a slug and a snail for the 40 yard dash.
Bottom line: don’t waste your money. If they put either in the $3-5 range, they’ll be worth it to make low poly game models.