The core problem with Genpo's Big Mind the way I see it is the lack of renunciation, lack of development of brahmaviharas and panna.
So you may have a glimpse of emptiness, of this universal experience. It may have a transformational effect, it may (more likely) just boost the ego. One could have such an experience with drugs and emerge no wiser. At best, it will motivate the person to seek serious training.
What is really needed is a letting go of all that's unwholesome, an insight into what is and who isn't - a development of wisdom. Otherwise one grows a big head and becomes what is sometimes called around Zen circles "an enlightened @$#%hole".
In traditional Zen training, there is a lot of letting go. The hardship the monks went through, their long training brought out all the clinging and defilements for them to see and let go, focusing single-mindedly on practice, dying the great death, they called it.
Great Faith, Great Doubt, Great Determination -> Great Enlightenment.
Or Big Bucks-> Big Mind -> Big Head.