I want to jailbreak my iPhone, should I?

I have an iPhone 6s and I don't know if I should jailbreak it. I want to but I don't want anything bad to happen. I know what to do when the iPhone 7 comes out. I have this iPhone forever thing where as long as I don't crack my phone, I can get the next iPhone for free. I backup my phone and use the backup before I give my phone to them to "unjailbreak" it. Or I update it if an update becomes available. But before I consider jailbreaking my phone, I want to know more about the security issues. I'm running iOS 9.2.1 and I want to know what security issues could occur if I jailbreak it. Also, if there are any providers that possibly make jailbreaks that has good security if they even make those.

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