Methadone is an opioid. I'm assuming by "pain pills" you mean other opiates/opioids so, relatively speaking, it is the same.
I wouldn't consider it on the same level as any other opioid actually. In addition to what you mentioned about it staying in your system a long time, which has risks such as being able to get physically dependent on it with less frequent use compared to other opioids, there are also the following risks:
- if you do get physically dependent, withdrawal is longer-lasting than any other opioid, and many people consider it subjectively worse than withdrawal from other opioids (although this may mainly be because WD lasts so damn long, I know that was the hardest thing for me)
- it takes a long time to take effect, which can lead to redosing when it isn't wise to do so
- it builds up in your system because the half-life is so long (if you take it again before the previous dose is eliminated you can OD on an amount that would have been ok had you not had any methadone in your system)
- the respiratory depression lasts longer than the high, so people often go to bed seeming fine and don't wake up
- also due to the respiratory depression lasting so long, people often will take more methadone or other drugs assuming the methadone has worn off (other CNS depressants exacerbating the respiratory depression)
OP - If you've been taking it a few times a week for years now I would hazard a guess you are already physically dependent, at least to a degree.