I believe the increased use (as I've read) of methadone for chronic pain, is due to ins. co. pressure. It's very inexpensive.
This doesn't mean that methadone isn't as safe as more modern meds (imho) such as oxycontin, or opana. It simply means that there's more methadone out there, as time goes on.

It's potential for abuse, again, imho, is lower as well.

Again, this is my opinion.
"Talk to your doctor".