Value of Subjugated Empires

[Harmonious Hegemony]

I am wondering about the value of subjugating an AI empire instead of just going on to conquer all of its colonies. The victory conditions relate to number of colonies, total population or total economy. Does a subjugated empire contribute to any of those? Or is the value just in getting them off of your back while you do other things (or do other AI empires, as the case may be)?

[Merker]

Well it depends on their number of colonies I think, the bigger the empire the greater your income. So a 5 colony empire will bring you something like 5k, and a 50 colony empire 50k. Don't expect to pay off your fleet from that income. In my AAR I had subjugated about 10 or so empires of various size and the income was around 150k or something.

Cheers

[Data]

The only value I imagined for subjugating an AI empire is to preserve him for late game, to avoid boredom.

[Haree78]

What I can think of:

Pros
Other Empires around means competitive Empires that are at war with the Subjucated Empire are less inclined to war with you also.
Related to that, by owning those Colonies instead of taking tribute from them you are going to make new enemies who are jealous of your planets.
That race may have a special tech that you are wiping from the Galaxy before getting your hands on it.
There may be trade in tech later that is pretty valuable.
Prolonging a war for some time is costly, sometimes you just want to let your people have a rest from their War Weariness. Also if you are at war on multiple fronts by subjucating that Empire on the left you can now move all fleets to the right hand side and be more effective there.

Cons
Less money
They are likely to have taken mines and planets that you want but now there is a reputation hit to take them.
If they are some dirty scum bags it could be someone who will try and hit you when you aren't looking and fighting someone else.

[Harmonious Hegemony]

Merker - How were you able to identify the 150k income from your subjugated colonies?

[Data]

It doesn't appear in the empire status screen but on the diplomacy screen.