Interesting that you should ask....
I like conventional starts, but I got a little tired of the challenge of running into aliens who've had 15-20 years to advance their empires and tech before I managed to get out of Sol system. (The game makes NPR generated later more technologically advanced, IIRC, based on the game's start date.)
So this game I decided to up my population to 10billion in my conventional start (I usually use 1Billion), as well as upping homeworld minerals by 20x to match the bigger population. Actually ran a 1billion start and then used SM to up the population, research labs, and minerals, since I inferred from one of Steve's responses that Aurora remembers your starting population and bases NPR initial population on that - I wanted to run into smaller, more advanced civilizations, rather than just making everyone 10x bigger :-) In other words, the game really does seem to be balanced for starting pops of 500m to 1b.
John