Thanks for your comments guy! Most of the parts have been painted by now, but still need some minor corrections; but the main painting work is over now. I now have to bring all those subassemblies together before glueing them on the bridge.
I definitely use PE parts for this kit. They are mostly used on the machine guns, as you have noticed. The single 20mm gun enjoys an extra PE framework and sight, while the 37mm shield uses shield hands (left and right), two handwheel mecanisms (left and right of the pintle), a hand crank conduit (with a modified handwheel), two footrest layers, as well as some other parts to be mounted on the gun itself (which should be ready soon). The double 20mm comes from another PE set, but I used a lot a plastic pieces on this one; the gun barrel and shield are white metal, and I used the PE ammo clip parts as well as the gun sight - but nothing more.
I chose to paint the inner shields of my guns in a slightly darker gray than the outer shield, as my research have shown. It's hard to see on my pictures though: I only use a webcam and shoot most of the pictures after sunset (and it's been raining for a whole week, so I didn't really see any sunsets). But I'll try to borrow a digital cam when the kit is built so I can share some better pix with you.
But taking pictures is no easy task when you have to protect your other models from your marauding cat, always eager to explore new forbidden territories (like the shelf where my planes are stored - by the way, the only model that really freaks her out is the Me262 and its aggressive sharky look). Here you have two pictures taken by a security camera showing the cat just a second after it has been located next to aircraft models, which had the effect of instantly launching an automatic and quite effective vocal alarm...