Interesting thread. I too have used xanax and adivan when needed and prescribed, tho I never have abused them. I never got how people did abuse them as I never experienced any "high" from them. SO, if that is the case with your friend than by all means, I would say he is sober.
The whole "are you REALLY sober" thing is tricky. I know that if I were active in AA, they would say that I am not sober because I will occasionally smoke weed. Well, tho it is not prescribed to me, I honestly only smoke a small amount to fall asleep as I have really bad insomnia, not to get effed up. On the other hand, the drugs that are often prescribed for insomnia can indeed be habit forming.
As another pointed out, so many recovering alcoholics smoke a **** ton of cigarettes and no one bats an eye at that. I think going through a pack a day of cigarettes is far more unhealthy than a few puffs of marijuana a couple nights a week.
And no, I am not substituting one substance for another. I drank to get inebriated, numb, and to forget. Totally not why I smoke weed here and there.
Sorry, sort of got off topic but I still think it relates and it is one of those things that has always bothered me.