In response.
I read the edit after the post, in fairness the edit didn't make it in my quote. The above statement about "pooling" and whatnot, tells me that you don't fully understand the TCP/IP protocol suite. Sure all our IP addresses are all connected in one way or another, but your above description doesn't even fit on a scale of 1 to 10.
Your statement that checking or trading somehow will allow you to see what the IP Address of the person you're checking is completely false. PlayOnline and FFXI are Client/Server applications and do not communicate peer-to-peer. The 3 screenshots below show the traffic of my mule in Windy Woods making purchaces from 3 different bazaars. I launched the sniffer waiting for a few packets to come in, tabbed to a character, entered the bazaar and bought something (cheap ;P). I did this three times, and on the second attempt, sending and receiving a tell from a friend. In all 3 captures, it only shows me talking to the server.
The highlighted text above (bolded by me for clarity) tells me that you don't understand encryption. Either you're using excryption or your not. It's not a light switch you turn on and off while the data is in transit. Even if you (or someone you know) broke the encryption (I'm sure the NSA would love to use your talents if you did) and you decrypted in real time, the client/server nature of the application does not give you and information on the person you're talking to.
From your apparent lack of understanding of technology and its implimentation I call bullshit on the statement above. You say you hacked, ok fine, I won't counter that claim. But to come here and misrepresent yourself and make some bold statements doesn't do anything for your crediblity. I echo people's comments that say it's a shame to do that to a game we all know and love. Best of luck in your future, may I not run into you in any game I play in the future.