Not yet, still at work until Sat, however I disabled port 88 on PT and just left port 3074 enabled. I was only able to get two games in and they were both glitchy, I was teleporting from place to place. I wonder if the host had a lag switch or something.
Anyway hopefully my unbeknownst little beta tester will play after school and I'll see if he notices anything, lol.

Anyway, did you ever look at the internet session logs when you were gaming to see what ports were being used XBL and what priority they were at?
If not I was going to do that tonight to make sure GF is working properly, (hopefully).