So, I found a way to combine the accuracy of NASA's Tycho/Hipparcos starfield render and the visual attractiveness of the
Milky Way.
The problem I have long had with this is that the galactic panorama is rendered using the galactic plane as a reference, whereas the Tycho/Hipparcos catalogue render uses Earth-centric coordinates, meaning the north pole is Polaris, and the equator of the texture corresponds to equator of Earth.
This is a problem when rendering, because the Milky Way is not easy to align correctly. Luckily with perseverance and, lengthy calibrations, I managed to approximate satisfactory settings for the two globes so that the textures are mostly aligned (there are a few anomalies but I doubt anyone who doesn't know what to look for will see them):

If you look at the object windows and the orientation matrices and positions of the starfield and galaxy spheres, you'll see that they required quite careful adjustments to align with each other.
The problem with this was mainly that the preview window absolutely sucks (though with 16384x8192 textures I can hardly expect anything better). It can not be used as reference at all, so I had to adjust the orientation of the spheres, then render the whole shebang, adjust some more, render again, and carefully move closer to a position where starfield and the galaxy would be aligned at all directions, or as close as possible.
This used to be a big problem when I only had 4 gigabytes of RAM; the rendering would often kick into the page file, slowing the workflow down immensely. Recently, however, I upgraded my RAM to 8 GB, and this has enabled me to work much faster with large textures both on GIMP and blender. As a result, I was able to finish the calibration process, and managed to produce a very flashy and not at all realistic skybox with great future promise.
This is a direct render from Blender:

And here are a few screenshots of the skybox in-game:





These shots were taken using default -fov 0.75. Here are a few shots taken with -fov 0.40, zooming into the texture and revealing the full detail:



In-game shots aren't quite as crisp as the renders, for obvious reasons - they're DXT compressed, which reduces quality, and the 4096^2 textures have one mip map level, which somewhat reduces the quality. I also think there is a way to significantly reduce the blurring caused by mip maps.
The biggest improvement, of course, is the milky way itself. Cool as it is, the Tycho/Hipparcos starfield texture is hard to use in a way that would make the milky way look good without filling the rest of the space with millions of stars that will make the appearance of the starfield quite noisy. This combined render allows that and is more flexible to customize the levels of milky way and starfield separately.
The other improvement is to objects such as Magellanic clouds, the Andromeda galaxy, Pleiades and other star clusters and other objects that now have a bit more flesh around their bones. Now, this version is rather extravagant and loud, but the improvements will also be in effect if they are somewhat subdued and desaturated, which would make them a bit more realistic.
In other words, more calibrations are required to active optimal visual effect for the intended purpose.
Expect to see derivatives of this work in WiH R2.
