I must say you are lucky to have a doctor who is behind you. Mine basically blew me off and tried to make me look insain. He said that IF they did leak any mercury my body could handle that as I was healthy.
He would not even humor me enough to run a test. I have not seen him since. That was two years ago.

Removing a root canal is about the equal of a tooth extraction. I too agree that redoing the root canal will not help you. You will still have a dead tooth and chronic source of toxic bacteria. Go for a metal free replacement. They have great partials now that are metal free. Likely they will remove the tooth, sometimes by pulling it, or making a tiny incision in the gum to remove it, and also cleaning out the dead and infected tissue/bone in the socket. Make sure they do this! If not it will not heal right, and you will have a cavitation. I know it sounds horrible, but this causes no additional pain than removing a tooth without cleaning it. Actually, not cleaning it out might make things worse. Expect to be sore and have some aching for a few days.