I recently kicked heroin. Then I started using methadone recreationally. I'm getting about as hooked on that as any other opiate I've been hooked on.
Infact, I'm actually starting to like it more than oxycodone or heroin. Because it last much longer. And precisely becaues it doesn't fuck me up. I can remain totally functional, act less weird than even on oxycodone, but generally feel good and my usual body aches are gone.
I'm not saying I wasn't totally expecting this to happen, but was certainly hoping to be able to manage things better.
At any rate, other than the fact that it's a pill and you get over the habit of shooting it, I really can't see where substituting one opiate addiction for another would really be helpful.
In the end, you HAVE to detox at some point. You HAVE to go through withdrawals.
Methadone is just keeping your physical dependancy going, prolonging the inevitable. And in the meantime, clinics typically recommend people be on methadone for 2 years, which undoubtedly will only make the withdrawals when you finally have to stop much much much worse.