re: "Well, AIP 8 has several things going for it, like:
-it's the only AI capable of using the Super Diplomacy and Super Manipulator SAs
Really? Are you sure and how did you test this (I can't think of a way)"
I had the Drath on AIP 11 for a while, when I was working on Autumn Twilight. During that time, I didn't see any of the "We've been bribed to go to war with another race" messages you'd usually see with the Drath in the game.
I don't recall, if I did it with the Terrans too at some point. So I can only assume it's the same with them. They are one of the few other races that does the bribes, and that might have something to do with their SA and how their AI is written. Though I could be wrong.
The only other race I suspect of doing bribes is the Korx, though I'm not 100% certain of that. There is also no way to set the races to use a specific sub-set of an AIP in the RaceConfig.xml, so we couldn't use the Korx one for the Terrans and Drath.
re: "-it's the best at researching better factories (AIP 7 is the worst, shortly followed by AIP 11)
This could be fixed with AIValue tweaking."
Though not guaranteed. I've set the AIValue for factories to 35 in the Arcean tech tree, and they still don't research them often enough.
re: "-it's okay at handling its economy (AIP 11 is atrocious in comparison)
I've seen very little difference between the economic sliders between AIP11 and AIP7."
Take a look at the tax rate of AIP 11. It's the only AIP I've seen that runs a tax rate of over 90%, or even over 100% occasionally:
That's an old screenshot from Autumn Twilight. I had the Thalan on AIP 11 for a while (like almost all of the races), and that's the result. Sure, they managed to win now and then, but it was a frustrating experience. It took a huge effort just to get them to research Industrial Adaptation I, and then they refused to research any of the subsequent techs, making them stuck on those hugely expensive factories. Don't even ask about Technology Adaptation.
The Espionage slider is another thing AIP 11 is just terrible at using. Sure, all of the AIPs handle it badly, but AIP 11 is the worst. It almost treats the slider like an on/off switch: it's either set to 0% or on max. Only rarely do I see AIP 11 adjust the spending.
re: "GC2 had one AI, DA introduced the 4 personalities."
From what I recall, DL already had multiple AI personalties. I specifically remember Frogboy talking about that in his AI Wars post and other Dev Journals.