Hey Daniel, thanks for your response.
I've not practiced concentration enough to have had these sort of experiences, so I can't relate to the other perspective, except from what I've seen in the psychedelic community.
Regarding experiences caused by psychedelic drugs there are three basic perspectives:
A) These experiences are delusional and unhealthy and should be avoided completely

These experiences can cause the mind to think and the body to feel things in a unique and interesting way, causing intelligence and insights not found in normal everyday experience
C) These experiences can allow people to access hidden information in the world, including information that is unavailable to all of their sense organs. Some believe they can act in the world in ways that would be impossible using a normal human body.
I take perspective B, but a significant percentage of people take C. So for example, you have people trying to read minds, and I do not mean using emotional or body language clues, but just trying to read minds. Or you have people who think they're literally communicating with aliens when tripping. For example, there were a significant number of people in the psychedelic community who believed aliens told them the world would end or drastically change in 2012, and then took these experiences literally.
My opinion is that anyone who takes perspective C either in regard to psychedelic drugs or experiences from concentration practices is going to have delusions of grandeur and spend an unhealthy amount of time trying to use or develop their powers.
The book also mentions things like Wicca. I'm non-religious so this doesn't really bother me, but I know a lot of Christians who would hone in on that and then reject everything the book has to offer. Of course, this is a problem with the reader and even if you got rid of those references most of these people would find another part of the book to object to instead. But when my family asks me wtf I'm doing meditating 2 hours a day and wanting to attend retreats, I'll probably just tell them "Vipassana meditation," and not provide reference to this book, due to their Christian background which could cause them grave concern if they read the part in reference.