is looking great arch, just two thoughts come to mind;

lower the contrast a little not so much on the renders but on the places that look overcontrasted... the really bright spots that lack any detail.

the fractal background is tight, im feelin it, i think it'd look better and help draw attention to the faces in the BG as well as the focal renders if you blurred the fractal layer in spots where you think needs it. mix it up, but make it flow together.