Try a redish orange colour for the deflector dish, i take it the blue circle is your impulse reaction crystal?
Impulse reaction crystal on a late TNG design I like the deflector dish just fine, it fits the design era of the ship.
So your good with green? I made it green to make it obviious that it is NOT a Starfleet vessel, and to give a clue to who helped design it....someone above figured it out. The Klingons.
As to the Impulse core vent....that shows that this ship is a warship, not a general Starfleet vessel. Again, this is not canon, just my contention.....In the old days (TOS, TMP) Starfleet was getting out of the warship building business. The last ship to carry warship systems was the Excelcior....The Ambassador class shows the move toward more peaceful designs.
Now, to the impulse vent....in the old days, the impulse reactor was one huge core centerline of the ship. It was actually a component of the warp core, drawing Dueterium directly as fuel on the way to the warp core. This system was good for military purposes, allowing both the impulse drive and the warp drive to operate 125 percent past tolerance for short periods. Not safe, but in a warship it is necessary. Now, as the mood in Starfleet shifted more to exploration and safety and less to defense, the impulse system was seperated from the warp drive system and fed by it's own fuel supply. This made the system more redundant, but provided less backup power for the ship.
My contention is that this design, as well as other Third fleet warships have moved back to the master impulse core design....hence an impulse vent like the old days. Visually, it just shows that this ship, as well as other Marine Corps vessels are just returning to thier roots.
I tried a redish-orange deflector, it actually looks better IMO. Ill post pics of it shortly.