My minor was journalism as if you had'nt noticed and please forgive my long windness as I have yet to figure out how to get around those "medical terms" without simple down to earth words. I feel strongly that the more info and understanding someone has the better apt they are at getting and keeping the best pain coverage possible therefore giving them a better qulaity of life,something even a few years ago CPers did not have. Sad to say many still do not for one reason or another and that can be affected by simply what part of the world you live in.
Morphine is a great pain reliever as well but once you have been on methadone and especially after 4 some odd years your not going to make that switch in a day or a week and get an accurate account of how well it is doing for you.
As tony said the methadone is masking whatever "feel" that comes associated with pain relief.
If you dont want to go back then I suggest sticking it for a bit longer it really has not been that long and you still are retaining small amounts of methadone in your organs and your body can pull on that for sometime in small amounts.
I have gone down in that sinking boat so many times over these 10 plus years that I have found thats ok as long as you remember to wear your life jacket you always manage to float back to the top somehow.