Just my 2 cents...
I only moved 10 miles away, and kept the same RO. I changed my address with both RO and VAMC. VAMC had no problems with mailing my meds to my new address. I didn't have a change of address, I would have missed about five letters from RO, all mailed after I called and sent a letter advising of my change of address. After every letter I received, I would call the 800# again, and ask what address they had on file for me. And is was always my previous address. But this is just my experience... And I just moved 10 miles...