Thanks! Presently I'm tweaking it a little. I'm adding a few small and subtle details (you'll have to really look to notice them) and tweaking some of the colours. The nacelle domes have been made a bit darker as is the nav-deflector dome. I've also added just a hint more of green/cyan tint to some of the hull sections.
Part of the colour issue is that colours look darker in SketchUp then they look when rendered. So it gets tricky to get shades just right.
In terms of size comparison you can see how this is distinctly smaller than the Constitution
-class even if the saucers were the same diameter. The dorsal is smaller, the secondary hull is smaller, the support pylons are much shorter and the warp nacelles are smaller in diameter and distinctly shorter. The Constitution
-class components are not only larger in general but also pushed out further from each other.