Well... One day I got bored after completely destroying an AI, so I started measuring things.
Now, first off, I knew that the diameter of the earth and other like-sized planets was about 12700 kilometers. I then proceeded to observe that a planet was just over four tactical squares in diameter. This made me realize that each individual square must be about 3000 kilometers across.
Next, I looked at the size of an Egg, the largest of the capitals. By estimating its size, it appears to be around 1500 kilometers in length and 500 in width. Now, it is the largest of the caps, so you normally wouldn't think anything of it except that if you look very closely at the top of it, you can see skyscrapers jutting out from it. Each of these has strip lights, suggesting windows. Now, since the Vasari are of a comparable size to humans, you can estimate the size of it to be about 200 kilometers in length and 75 in width. Now a population of about 10,000 would work on the smaller version, but the to-scale version would have to have a crew in the hundreds of thousands.
[Relatively] Moderate Difference.
Next I measured an Akkan and again looked at the strip lights. It too is about 1500 kilometers in length via the grid system, though only about 200 in width. Then I looked at the strip lights. On the akkan, they were even larger! You could see individual windows on its port side in multiple rows representing individual decks. That is all well and good except that to be 1500 kilometers in length, each window would have to be a few kilometers long. By estimating the length of the Akkan via the strip lights, I came up with only three kilometers. This is the size of ship that would hold 5-6000 crewmen. Not to mention that it is a comparable size to the Egg when the texture in fact suggests that it is a fraction of the size.
I then proceeded to look at the fighters of the Akkan against itself. This confirmed my earlier belief that each small window was an individual 5-6 foot window as I looked at the size of the cockpits. I then proceeded to fly a fighter up to a planet and using a bug, flew it "through" it (technically, just inside the white circle so it was halfway in the planet) and discovered another problem. Each fighter could comfortably cover a small state like Vermont, or Massachusetts. This means a hundred kilometers in length as opposed to about 10-15 meters.
Then I looked at the size difference between the stars, gas giants, and planets. Once again, completely disproportionate. Gas giants are twice the size of planets when in reality they are 12 times larger. Stars appear to only be four times the size of planets when they are really more than a thousand times larger.
Now, I'm not saying that this is a discussion of a particular problem or complaint as this is just an observation. I'm not saying it should be fixed as I'm sure this system works best with gameplay. I just figured I'd say what I found when I got bored...