The one complaint or issue I have is misleading direction of lighting within the game. I am assuming that you are going to use these planets for spobs. The way I see it, everytime you jump into a new system, there will be a difference in shadow direction between the planet and the ships. Your planets all have different light sources/directions but your ships will (probably) all have the same light source/direction.
I see some rough solutions, but nothing that will fix everything. First, you can keep the whole plane of the screen along the x-y axis and so the player only sees the top of the ships. Then just put the light source when you render above/behind the camera so that no shadows can be seen on the ships at all.
Second, you could have an entirely different set of ships with a different light source direction, one for each different syst. Assign each ship to a unique dude resource, then populate a particular syst only with its unique set of ship/dudes. This means a heck of a lot of more-or-less redundant ship graphics with the only difference really being the shadow direction.
Third, you can ignore the problem. It is just a minor graphics issue, nothing major.
Fourth, you can start making all of your planet renders have the same light source direction. A bit of a compromise, but the simplest and shortest solution.
Just some constructive criticism on a bunch of images that look pretty good now, outside of EVN.
Werhner