can anybody confirm it's working please, I've tested and simply don't see a difference
It works for me and all I did was edit the config file as described, I didn't have to enable anything anywhere else. I increased the planet texture size to 16384 and the GalaxyBackground texture size to 4096.
Under the <Environment> section I also increased these settings to 4:
<Ultra>
<LocalisationName>$QUALITY_ULTRA;</LocalisationName>
<Item>
<Feature>GalaxyBackground</Feature>
<QualitySetting>4</QualitySetting>
</Item>
<Item>
<Feature>Planets</Feature>
<QualitySetting>4</QualitySetting>
</Item>
<Item>
<Feature>DamageDecals</Feature>
<QualitySetting>4</QualitySetting>
</Item>
</Ultra>
I don't know if changing those settings beyond 3 did anything but the bigger textures definitely made a huge difference. I run ED in 2560x1440 with V-sync enabled and I get rock-solid 60fps except for a ~2sec stutter when entering hyperspace. I can live with that because the visuals are spectacular and there is no other hit to performance.
I have a pair of HD7970s, an i7-4790K and ED runs off a striped pair of SSDs. Your mileage may vary.