I have some more addition info on integrating. Not much but some.
At 2.64 reputation (rounded up to 3), 2 baseline, 1 same religious, and last but not least 1 same culture. Add up to about 7 diplomat cost per month. I could raise reputation by another 2 from influence 5th idea.
Notice: I used the reputation via catholic Papal's influence and increase relationship to 100 mission to gain another reputation. I also had about 82 legitimacy which lead to the .64.
I completed the third influence idea which gives 25% discount which is already baked in the following numbers. Perhaps I should have take the number before I completed that discount. Oh well no matter. Can't go back in time ironman. Still I did manage to reverse engineer the non-discount cost.
Norway at the moment is at 75 total development. That can raise or lower dynamic over course of a game. I will assume that it is static. 75 * 6 = 450 with 25% discount. Without it is 75 * 8 = 600. So you can take any other development and apply 8 or 6 per development for any other personal union.
At 7 diplo-annex it takes 5 years and 5 month. If I reverse engineer the diplo-annex total cost going from that. It comes up to about 450 max.
(5*12 + 5) * 7 = 455 (technically between 449 and 455)
In-game number is 450. We will onward use that 450 and round up number in a lot of places since that how it works in-game by paying per month.
If I continue using 450 at 9 reputation per month. The time to annex is as following.
450/9 = 50.
50/12 = 4 years and 2 months.
If I go back and take 25% discount off it comes up to 600 total cost.
Now if I go back and take the one culture off the top using 600 number and 6 per month. I can figure out the time it takes if I didn't enforce union.
600 / 6 = 100 months.
100 / 12 = 8 years 4 month.
If I had 9 reputation (with 5th influence idea) the time will be:
600 / 9 = 66 6/9.
67 (again rounding up) / 12 = 5 years 7 months. Clearly there is a somewhat diminish return the higher you go regardless of the total cost.
Which isn't that bad all thing considered. Beside having higher diplo-annex speed also drain your diplomat monarch point balance much quicker. Getting the norway's land let you reduce Sweden's strength vs you much quicker. Otherwise you will be dealing with more often rebellion if you pick the +1 stability and monarch point boosts. Let not forget the estate 100 monarch points each 20 years. You can easily afford it all thing considered.
It depend on if your ruler is lucky and have high diplomat skill. I say go for it. If nothing else especially if you are diplo-annex someone with high developments. This is of course assuming that somehow I maintenance 9 reputation for more than 5 years (unlikely since some reputation are temp boosting) so don't take what I say here literally and figurative.
There are other factors that make this more complex as well. If you just happened to fully integrate from the monthly chance to inherit at the first month. All of your investment would have been for naught.
Only do enforce culture if you have surplus diplomat monarch points and plan to keep both Norway and Sweden under PU until integrate. It will not always be the best thing to do every-time.