Methadone is as addictive as heroin, but withdrawal is different. Whereas on H the wd is extremely intense it lasts a relatively short time, 5-7 days, but as soon as you start feeling better, day 3 or 4, you are OK if only from the fact that you notice feeling better and get a big boost from that. With methadone the wd creeps in much more slowly, shadow like, is not as intense but seems to last much longer. Nonetheless, you can detox from methadone relatively easily by locking yourself in a cabin with no access to drugs and have someone bring you minute qty of heroin after 48hrs, 24hrs later half of minute, 24hrs later a nano particle of heroin, 24 hours a placebo. Just make sure you have to do something so you dont feel so sorry for yourself, it aint that bad. Some drugs you wouldn't expect seem to help with wd from any opiate, Clonodin in particular (hypertension drug), also Kratom, a non-opiate opiate substitute from SE Asia helps, you can buy it on the net.
all in all, as bad as wd is, it is not life threatening and subjects invariably experience symptoms they expected so it's also very psychological. People who did not know they were addicted thought they had a flu.