The only thing about the design I'm not a fan of, is the spoilers and spikes... the big ones. I'm not saying that I don't think that they should be there, I'm just saying that I think that they're a little too prominent. I was gonna suggest sloping them inwards more, but the thought just occurred to me that you might want to go against the traditional Demon configuration of ventral spikes, and instead have them angled outwards and chunkier, sort of like echoes of the nose "teeth" portions. This applies to both the rear-most ventral spikes, and the mid-position ones... IMO. I'd also suggest making the dorsal spoiler somewhat chunkier. That is, take the front of it, and move it forward, then take the rear of them and stretch it towards the back of the craft, so they appear more sloped. It may necessitate making the tail end of the ship a little longer.
That said, these are my simple suggestions, and nothing binding. Make it YOUR way, and make it YOUR ship.
