Well thanks.
I concur the wings are really plain, even after a lot of tinkering it still doesn't show the normalmap, the glossiness nor the SSS in the way I wanted, but I'm done with this one for the time being.
Setting materials can be a very frustrating experience when every preview render takes at least 30 minutes of my day, and for such stuff that needs a lot of testing, loading/reloading of images it gets seriously out of hand
Maybe I'll come back to it later when I upgrade my machine and I'm able to render stuff with more than 1.5 million polies, so not only I won't waste that amount of time rendering but also I'll be able to use sculpted pieces.
About the AO and everything else, a piece of
mea culpa in form of advice too: I set up a lot of composition traps along the way, as this piece wasn't thought from the ground-up with lighting setup, posing and such. So yeah, don't do as I did, and much headaches won't be had!
Edit: Downloading the borders, will test it later.