If it was legal to do so and was properly prescribed by a physician, absolutely. In a medicinal context, it is often even stripped of elements that can make a person high, but even if it wasn't, that high is as you point out much less significant than the high given by current legal opiates.Given the huge and growing body of evidence of the efficacy of marijuana as a treatment for MS, chronic pain, etc. it's really upsetting that it's still illegal for medicinal use in so many places. With that said, if a Christian is in one of those places, I personally believe there is an ethical obligation to obey the law even though it will result in suffering. (I believe there is an ethical obligation for non-Christians to do the same.)