Taii Frigate Engines image - HW2 Taiidani Project Development Team

Well, to me the most important question is what you see as the most valid reference, the concept arts or the in-game ships.

I guess you want to base it on concept art because those have clear curvatures, not like the HW1 low-poly models, and because they are the initial representation of the idea, they are the originals which are the models based on. But on the other hand I'm pretty sure that most of the HW1 players would see the model as the only original reference and the HW1 models are actualy the way it really looked like at the end. So where exactly you define your original reference? You would probably have to answer that to make the communication as clearer and smoother as possible.

My personal oppinion is that model-wise (proportions, basic geometry) it should be based on the ingame models, but closely follow the details and curvatures from the concept arts. So it look like the original game models but it's as detailed as the concept arts.
And I would take your statement "the copy-paste of original HW1 texture" as a compliment, because it's as close to the in-game original as possible and it's hi-res like this. Only thing I don't like about the engine texture are the jets/nozzles (which one is correct?), the star shape does look like an easy way to make it look effective with just a simple trick.
And didn't you say somewhere that it could use some more detailed mesh around the jets? I think you did and I agree with that, goblin mesh rims would be nice.

Nozzle.
Star shape is for disabled engine only, enabled engine looks in another way.
Details are useless. Explaining why.
You can see the details on the rest of the hull, for example, 'cause they're shaded. But full-glow details in the engines won't have this shading and will be nearly invisible. Well, actually, depending on what exactly to add.