I just finished up The Supreme Self by Stan Trout, which is one third autobiography, one third history of mysticism, and one third how different universal questions appears when Spirit awakens to itself.
As it is written by somebody who is intimately familiar with Big Mind, the essence of the various traditions is brought to the foreground and presented in a very clear and simple way. (Which by necessity means that the diversity and difference in flavor goes into the background, leaving out some of the richness.)
One thing that came up for me is the complementarity of Atman and Anatman, of Self and no-self, and the traditions emphasizing one or the other.
There is the Self, aka Buddha Mind, Big Mind, Brahman, and so on. The field of seeing and seen, of awake emptiness and form, as that beyond and including all polarities. It is "I" as awake emptiness and form, as the field as a whole, as Big Mind.
And there is the no-self, the field of seeing and seen absent of I anywhere. It is the field of awake emptiness and form awakening to itself as a field with no center anywhere, with no I as any segment of itself. There is doing, but no doer.
There is a beautiful complementarity of Self and no-self, and this is expressed within each of the traditions talking about Atman or Anatman, whether they emphasize one or the other in how they talk about it, or as a path into this realization.
The Big Mind process strikes me as a practice that especially well includes both. We get to explore ourselves as Big Mind, as Atman, as awake emptiness and form, as the whole beyond and including all polarities. And we get to explore the no-self, the absence of I anywhere in this field of awake emptiness and form, including in all the different personal and transpersonal voices. They are all there, available, yet each one of them inherently absent of an I.