I understand the reasoning behind the unique IP thing, but I do have a bit of a moan to make, sorry.
If I want someone to nation sit for me, while I'm off on holiday, I'm going to ask someone in my alliance. Makes sense right? I trust them more than some random.
But, if we do this, we can no longer aid/war/whatever. Which is a bit of pain, since we're in the same alliance.
Just wanted to get it off my chest.
Sorry.