The last one with the GI looks good on the skin, because you can at least see detail in the shadowed areas, but it's definitely not worth the hour+ rendertime compared to the 8 min render. The hair looks just as good in the 8 min render as in the GI one, the main difference being in the shadow details. If you are able to get the GI one down to, say 10 min, then it would be worth it, but you'd end up with lots of artifacts. You'd better test ALL of these in a real animation, because what you see in a still might not translate well to motion.