I have had great experiences smoking changa and having therapeutic breakthroughs in my understanding of my life, biases I was unaware of, and new perspective in approaches to tough problems.
Yep! I am a big proponent of drug testing/harm-reduction and dosage is a huge problem a lot of people face. With experience comes a good sense of what you can handle but for those new to this check out resources like Erowid (we love you).