I got Galactic Civ II Ultimate Edition recently from Steam.  After trying different things and restarting about a dozen times to learn the mechanics and the tech trees, I have played 1 full games with abundant habitable plants on large map.  

In my second full game (ongoing) my difficulty level is "Painful," immense map with abundant habitable planets.  I'm playing a customized race with Torian technology and Super-Breeder.  I added bonus points to the AI to make them better.  

It didn't matter.  

I've colonized a third of the galaxy and still growing like an unstoppable cancer.  Without the super-breeder trait, I've found that your expansion process stops around colony 15 due to maintenance costs.  But with super-breeder, you can keep on expanding because your pop and your econ catches up.  

Also Torian tech tree is probably the best in the game.  Central mining is equivalent to a manufacturing center, except several times cheaper and only costing 3 bc in maintenance.  If you start on a planet with 300% manufacturing bonus tile it's even more amazing.  Central Farming and Temples of Memory are super-cheap, super-low maintenance boosts to both pop, influence AND happiness and can be spammed in every planet.  Even schools are excellent due to their cheapness and the 1 bc maintenance costs.  The combination of those 4 buildings is kind of like being the Thalans and being able to put their Hyperion Matrix on EVERY planet.   

Furthermore, your tech tree allows you to research pretty much anything you want.  You want marketplaces? Go Xeno Economics.  Want more production? Xeno industries.  Happiness issues? Go the healing pool route, which at its peak provides a building with +50% happiness.  Need more pop space? Get Xeno farming.  Influence? You have the entire cultural domination route.  More research? Xeno Ethics and Neutrality Research.  Government? All the way up to Star Federation.  

Compare that to some of the other tech trees (like the Thalans or the Yor) which are missing some very important tech routes (like for example farming or superior governments).

Combine it with customized double-speed colony ships (two ion engines, no life support module) and the net result is that your expansion is unstoppable and FAST.  Your buildings are cheap and low maintenance.  Your pop growth is amazing.  AND you can customize your newly settled planets to anything you want, thanks to your grab bag of research options.  

Has anyone else found this to be the case?