What are the pros and cons from removing a province from the HRE?

I play as Venice, which is not part of the Holy Roman Empire (HRE), but is surrounded by provinces that are. Conquering those provinces will not remove them from the HRE, but you can do it manually.

I know it will "upset the Emperor", but not by how much. If I remove several provinces, will the negative opinion modifier stack? Will other member states care? What about non-members?

Will it affect local rebels?

Also, I guess it will remove the "unlawful imperial territory" event, but that only fires on provinces which are not cored anyway.

What are the pros and cons from removing a province from the HRE?

Solution 1:

If one of your provinces belongs to HRE but your nation is not a part of HRE and you make that province leave the HRE then the following effects would occur

• Relationship with Emperor -50

The province must be a core province to enable the ability to make a province leave the HRE.

Not sure if it stacks.

Having a province within the HRE increases your Imperial Authority. This in turn allows you to pass reforms if you ever become the Emperor of the HRE further down the line.

Any provinces bordering the HRE (including 1 sea province) may ask to join the HRE unless your nation is more powerful than the current Emperor.

If your capital is a member of HRE you become a prince of HRE and therefore can be elected Emperor. This has it's own benefits.

If you're annexing HRE provinces then it is best to core them as soon as possible as the Emperor will soon declare them "unlawful territory" and demand there return when not cored. If you refuse you get -33 relations with Emperor, -10% production and -50% manpower within the province concerned.

Solution 2:

In addition to DMK's answer, some additional notes:

• Removal of province from HRE reduces imperial authority by 1 -- not the best way to destabilize the current emperor, but if significant swaths of land are to be removed, that can change the course of events. Conversely, if you plan to become emperor yourself, remove all possible provinces from HRE if IA is zero -- adding them again after becoming emperor will give you 1 IA per province.
• The Emperor gets "Imperial Liberation" CB after declined request for returning of unlawful territory for 60 months, which is a low-AE, low-cost, high-prestige CB to liberate the HRE provinces in question.
• The Emperor has a permanent Imperial Ban CB against non-members holding territory. If the emperor doesn't have other CBs against you, this effectively precludes them from starting an aggression against you (of course, it doesn't affect their participating as allies in other conflicts).

More info on HRE at eu4wiki.com