Oh wow, this is looking verruh, VERRUH cool.
About the redish stuff, I imagine it could very easily be a kind of extremely tough ceramic material, in which case really it would only need a good shine map on those parts to give the proper effect. Don't be afraid of using it anywhere you like - it's an important colour component!
I have four not-terribly important suggestions - so if you don't want to on any of them, no worries.
1) The three large rear chunks just in front of each of the fins currently have a seam line running down the middle of each one. (The topside one most prominently visible in
this pic) I would suggest merging these seams so they form a continuous chunk, as the scales plating effect definitely lends itself to larger curved surface areas rather than smaller segmented ones. Also in that pic, other than that topside chunk, there's nothing with such a distinct line running down the centre, and I think it would look cleaner without it.
2) The retail model's neck texture has more of a 'horizontal lines with lots of recesses' theme to it, which I'd say is an important attribute of the neck, and it would be great if some element of that could be modelled in. I think such recesses would work really well in augmenting the 'layered hull' kind of effect you have going over the rest of the ship, as well as more clearly defining the neck section.
3) There is what looks to be a flat surface with a straight edge at the back between the lower two fins on the belly - If that is the case I think replacing that with the kind of curvy layerd detailing seen on the head surface would be great. Or at least the straight edge - that's what caught my eye as not quite belonging!
4) Hmm this one will need a pic, so I may as well label the other things on it as well.
Anyway this suggestion is to pull the 'cheek' of the head down to where the red line is to cover more of the side, as this will make the head easier to texture in-line with retail colours and also remove the kind of 'thin ledge' bit marked by the blue line, which I don't think quite fits with the rest of the look.
Oh and the smallest niggle is those structures attaching the axle of the fin-hinges to the hull - the engineery part of my brain would looooove to see them beefed up a bit. Might also be very cool to separate the fins (if you weren't going to already) to animate them folding in during subspace jumps or something.
Anyway, fantastic work - I look forward to seeing this one in-game!