[Suicide Junkie]

One thing you missed was the supply usage, and the rads cost of the G-spike "addons"

Two questions about natural merchants:
1) Do people actually use natural merchants that often in the regular game? IE: Will this simply help balance its use?

2) Is it really that advantageous? The scale of all building is altered by the same factor; IE even though the spaceport takes longer, the resource facilities take longer (about 7 turns), too.

I imagine you would place all the extra population immigrating to the new system on the spaceport planet first, so your spaceport will see a higher build rate, and by the time your other colonies actually need the spaceport, it should be almost done.