You all seem to be missing the advantage and uses of autocephalous. It allows every king to excommunicate within but only within their own realm, every vassals to request claims: within their own kingdom/under there own liege king. For maintaining realm stabilty within a large empire spread over multiple (byzantine 5?) kingdoms is really fantastic, in fact its almost perfect. Every one of your lesser vassals kings (sweden, lappland, estonia, etc) can now get divorces when they wish if they need them, cos its their own vassals giving it to them. No fear of an obdurate religious head making their bloodline die out.[.quote]
How is that an advantage to the player? Why should I care if my vassal kings can get divorces when they want them?
It prevents minor vassals using religous claims to spread beyond their dejure kingdom and it stops the kings excommunicating each other, you and your family members/heir! that alone is massive!
Again, how is that mechanically an advantage to the player? Yes, I think most of us would like to see our vassals just control there de jure lands (there's something satisfying about having the map kept tidy like that) but it's not that big a deal mechanically--just outlaw internal vassal wars (and lots of people find external vassal wars an easy way to expand). And anyway, even if they can't fight each other, vassals make a mess of things with cross-marriages leading to kings inheriting lands outside their de jure boundariles.
[quote[ Also if like me you spread your dynasty and use THEM as your duke/king tier vassals it lets you sit in tanistry/elective gavelkind with no real issues. It doesn't matter if Im now playing the king of norger or if my 8 year old heir gets deposed in a regency from the emporership and is now the vassal queen of wales: I still have my pet religious head and sooner or later I will reinherit the title of emperor: hopefully before the ai does TOO much damage to it ahem.
Its honestly a great tool: but its an allen key not a hammer. Temporal leadership is a hammer, hierocratic is a screwdriver, first is great for a monorelam/small realm, the second is great if your a 2-3 kingdom empire and able to keep all the kingdoms under your own grip. Once you get bigger though? you start looking for more options.