Injection can't really be done on the thinnest thin skin because there's just not enough material to inject into very well. That's why the really thin skins out there (like 0.03mm) are v-looped. I prefer the look of injection and think it looks much more realistic than lace. The hairs go in a uniform direction, like real hair does. With a lace piece, after a few weeks you can have hairs going any random direction. I see photos from members here and there will be a hair coming out to the left, the one next to it coming out to the right, the one next to it going straight down etc. Real hair does not grow that way. Also there are the knots, which are really bad on darker pieces. If anyone saw my crown close up they'd say "WTF". Injected thin skin doesn't have knots so you get a realistic scalp look. But the hairlines do not look very good in my opinion. That's why I think an injected thin skin with SFS front might be the best combination.
I did see one skin hairline that looked pretty amazing but I don't know if it is injected or v-looped. Here is the video. You can skip to 2.40:
http://www.youtube.com/watch?v=fw4FE6RjG...re=related
The problem with this skin is even after he cuts off that excess base out front, there will still be a line and people will notice it when certain light angles cast a shadow down. There will be a big straight line across his forehead. But the ventilation is the most natural I have seen yet. If there was a way to make the front edge taper thinner to the very edge it might work, but this would be a whole new concept in base design. Someone with the technology should try it.