i changed address in april 2004, and i sent the AR-11, it work for the law but it does not work for the USCIS, i did not call the USCIS, but I contacted my lawyer and he sent a letter to Nebraska about the address change, immediately (he did in June 2004), i saw a LUD in my case and i received a letter to confirm my address.
I received my 2FP to my new address in Nov 2004.
For experience and my friends's experience, your lawyer should send a letter to the USCIS, because the AR-11 is not enough.
Hope to help you!!
RBulus