I was on suboxone for two years in CA and then I moved to Singapore, where I found out that buprenorphine was a banned substance. So every week I crossed into Malaysia where they have methadone clinics everywhere. It came in 200ml bottles and was a thick brown liquid with a slight sweet taste.
I had a very heavy habit and treated it with a hefty course of bupe. I had used methadone in the past though. The Malaysian doctor asked me what my dose of methadone was; I told him it was 120mg. He answered by starting to prepare an injection of naloxone in case I was way off in that dosage and would OD after the drink. (You use a typically a 5ml syringe, draw the methadone out of the bottle, put it in a glass). I knocked it back, and he said he wanted to observe me for ten minutes. After ten minutes I stood up, thanked him, told him I'd see him next week for four more bottles (I had to sneak the bottles through customs into Singapore because methadone is illegal there too).
Methadone can help save lives, but I hated it. It's just nasty. First of all, it makes you sweat like you just ran a mile all day, even in an air-conditioned room. You have to take two doses a day. You have to carry it with you everywhere you go. It's a clumsy drug with a lot of annoying side effects. Bupe is much more precise, clean, convenient.
BTW, kicking the methadone was a hundred times easier (yes, despite what we've all heard about its WD) than kicking Thai dope. It's mild. It lasts kind of a long time, but little things like a benzo here and a drink there make the WD much easier. With heroin? Forget it.