Argh,
Have you also noticed that UPGRADES take place all at once? You cannot upgrade one or a few facilities at a time, it has to be all of them? This can be a problem if resources are tight and you've got a large planet to upgrade. You have to spend a lot and get no returns for a long time before the upgrade takes "all at once". I've pointed out the contradiction of forcing build to 'one at a time' and upgrade to 'all at once' before. Would be far more flexible to have it the other way around, but would still be better to have both the same. In other words, we've currently got the worst arrangement! Ringworlds and Sphereworlds would actually be useful, too, since it would be possible to fill one in reasonable game time.
I've altered population modifiers in my own stuff. Planets get to 200 percent production bonus at 4 billion and top out at 500 percent with a fully populated sphereworld. Since the AI is so cruddy at managing population this amounts to another advantage for human players, though.
In a human vs. human game it would provide some realism. You'd be encouraged to build more things at large population centers because of the much better production time.
[ 28 December 2001: Message edited by: Baron Munchausen ]