His book "Mastering the Core Teachings of the Buddha" is available free link or you can buy it at Amazon for $39.95.
In various Buddhist forums there is quite a bit of doubt about his claims to being an arahant, such as, Dhammawheel discussion about Daniel M. Ingram
But he seems to be a very adept teacher and I am wiling to give him benefit of doubt till I complete reading the book.
One paragraph from the foreword had me hooked .. it is exactly what I wanted to hear from a modern Buddhist teacher
Not so much Sex Pistols but more Dire Straits for me .. but I think he is speaking my language. Discovering an unconventional teacher of my generation is refreshing.The world is brimming with very nice and friendly dharma books. There are hundreds available on the shelves of any mega-bookstore. However, I believe that there is room for a book that sometimes conveys its message in a very different voice, though I respectfully give you the option to choose how much of that voice you want to hear. It is the unrestrained voice of one from a generation whose radicals wore spikes and combat boots rather than beads and sandals, listened to the Sex Pistols rather than the Moody Blues, wouldn’t know a beat poet or early ‘60s dharma bum from a hole in the ground, and thought the hippies were pretty friggin’ naïve, not that we don't owe them a lot. It is also the unrestrained voice of one whose practice has been dedicated to complete and unexcelled mastery of the traditional and hardcore stages of the path rather than some sort of vapid New Age fluff or pop psychological head-trip. If that ain’t you, consider reading something else.
As a highly regarded senior meditation teacher and scholar (who will remain anonymous) said to me after skimming through an earlier draft of this book, “Most Buddhists are just aging Boomers who want to do something to feel better about themselves as they get older and are not really interested in this sort of thing.” I wish them great success in getting those valid needs met and so I must reluctantly advise such individuals to avoid reading this book or at least the chapters marked with a star. This is simultaneously an admission of the limitations of this work, an invitation to adopt a more empowering view of what is possible on the spiritual path, and a warning.