I've Been Diagnosed With Ankylosing Spondylitis. New Doctor Just Switched

I've been diagnosed with Ankylosing Spondylitis. New doctor just switched me from morphine ER and Oxycodone IR to Methadone and Percacet, because he said the former would harm my organs and bodily systems, but the latter would not. But Methadone and Percacet are still opiods, so it seems to me that these, too, will hurt my bodily organs, etc., just as much. Am I right about this?