Shaun, when we worked on Omar's helmet, we copied the actually helmet found on starwarshelmets.com.
If you have a moment, you might want to redo the tip of the left frown and get close to the references below.
I know it will be a task, but it stray away from the ROTJ frown. I hope this helps.
I studied your beautiful helmet over and over and I can see you painted a little more on the "lips" area.
I'm not sure if it will be an issue, but let's see what Tony can find on it.