As usual I'm a little late to the discussion. In my opinion Tessa has summed it all up pretty well for you.
I also take Vitamin C every day to help prevent spread. I've been told that maybe nerve block(s) directly before and after surgery is preventative as well. I have had this same dilemna over having a colonoscopy and that doc. summed it up pretty well for me. He said "the RSD will not kill you, at least not directly, but colon cancer would." So, your other foot problems could over take your abilities anyway. It's such a hard and personal decision.
I just finished my SCS trial and believe me I'm worried about the "spread" issue on that as well. It was agonizing just trying to decide on the trial. It's frustrating that there are just no guidelines or prognosis on this disease!!!