Using methadone to break free from heroin abuse is relatively painless, and will allow you to function normally in society. But methadone is in itself a very addictive substance, and a lot addicts who try to get off methadone remain users many years into treatment.
If Suboxone works as well, is easier to get off of and you can take home a month's supply at a time - why would anyone still choose methadone???
Watch a gripping autobiographical documentary through years of heroin addiction, by Scottish filmaker David Scott.