in no way do i assert that what i do is right for every Christian. but as of right now, today, i have no qualms about what i'm doing, because it has poses none of the risk you reference for me.
if i didn't have the Holy Spirit (and confidence in God leading me and my life) perhaps i'd be more worried about every single risk life has to offer, including your reference of "crossing a line".
in my narrow example, i think this is exactly the kind of situation that God wants us to be sensitive and confident in His leading our lives.
like almost any activity that has no absolute, black and white instruction, i would say that the class i've described falls under the heading of acceptably led by my conviction and the Holy Spirit as to what is right for me.
the Holy Spirit has led me in ways that aren't expected, popular, and in situations where my judgment was flawed. He also confirms things for me when i need that clarification. i don't think God wants us to live our lives completely afraid of any and all risk, as to put ourselves on the shelf and not trust His leading.
i also don't consider this a "risk" in the sense that you seem to make it.
most alternative medicine has roots in eastern religion, and yet, many Christians seem to find that a very acceptable, if not preferred choice.
finally, i've become quite chummy with the instructor and a few other students, and i consider it one of the opportunities God may be using me to be a reflection and witness of God's love and truth.