The above answers are pretty solid, the only unusual thing I note here is that you can tolerate large amounts of cannabis. From my personal experience and anecdotal reports from fellow opiate addicts, cannabis can end up being even harder to cope with than full-on psychedelics in terms of dragging you into a state of self-hating rumination without the transformational insight of hallucinogens.
I'd guess you have been using cannabis regularly for many years, probably since before you started up with opiates, and have pretty much built a tolerance to its effects, not to mention smoothing the experience out with opiates (and possibly benzos as well?). So you wouldn't be affected as strongly by the kind of negative introspection that cannabis can provoke in people whom it hits hard. For me, smoking pot was a surefire way to end up in tears agonizing over how much of a failure I am for my addiction(s) to other drugs. In that sense, it was like my "anti-drug" as the corny PSAs in America used to go.
Real psychedelics, on the other hand, probably do hit you hard enough to brutally expose you to a confrontation with you unconscious guilt/shame/fear. Not that such an experience is without value; many people have said a psychedelic experience at some point in their process of quitting opiates opened up new horizons for them where they could imagine severing their dependence on opiates without believing they'd never be happy again.