In fact, I think the GFFP solution is already massively discouraged due to the time it takes to expand your economy.
A major limiting factor for expansion is population. I can build construction factories and research labs and components for ships faster than my population grows to support that expansion.
- 25bp per CF tech and a 50% governor + 45% sector governor bonus = 2.85 years construction doubling time = 35% annual construction growth (splitting equally between CF, mines and labs gives you 11.6% growth = 23.4% growth that requires population)
- Maximum population growth is 10% for smallest populations, around 2% after bonuses for capital planets. Your population growth *always* loses.
- Therefore you have roughly 20% of your production base growth unused because your populations can't grow fast enough.
- And this already assumes you have a large proportion of your population in the high growth 25mil colonies. Which can't do anything effectively except mine. (and if you're going for population growth, you need lots of colonies, which is difficult to find, much less find on planets with minerals worth extracting)
Integrating a second homeworld size population, with their attendant facilities, production and research, effectively increases your production base one fold.
I would normally use GFFP in most 4Xs, simply because I cannot spare the attention span needed to build troops, transport, and invade. And then deal with subsequent uprisings and other problems. In Aurora, this is easy since your attention span is effectively as much as you want.