Heavy smokers may feel different when stopping, may have a few sleepless nights due to dreams returning, may be irritable, feel bored, but it is not at all comparable to those coming off a heavy opioid addiction.
There is no equal disadvantage. If all heroin addicts were to magically over night turn into cannabis addicts and no longer be heroin addicts there will be many advantages and next to no disadvantages. Crime will go down. They will become employable, they will be able to lead "normal" lives. Disadvantages? I am not really thinking of any, let alone any that are equal