It's interesting. I know that this was one of MDMA's original uses before it become renowned for being a club drug.

I'm not sure how long lasting the change would be. I think the reason that therapy is so useful is because it retrains how we think about and approach situations, and it shows us that we are agents in our own change. It empowers people. But using a drug to take a sort of short cut to achieve intimacy/openness will not reinforce these ideas. So while he may in fact open up to you during these sessions, it will not establish a groundwork for continued openness, and it will probably not let him feel he is empowered in his own efforts to change. It will not show him that he can approach situations differently. That's just my opinion.

I have heard some talk of using MDMA and even some hallucinogens, in very small doses, for therapeutic reasons. Having had experience with a hallucinogen, I can say that while you do experience a sense of awakening and connection and FEEL changed, this isn't a long lasting experience you can take into your life to build a healthy infrastructure in which to live.