If it weren't for the dualist aspects, such as spirits and reincarnation, I would be a Buddhist in a heartbeat.
I'm unclear about your reference to "dualist" aspects. There are popular versions of Buddhism especially Tibetan that include these things.
I think of Buddhism as a top down religion which provides a popular religion for those who need it but is always open to going beyond those forms.
The Buddha experienced a fundamental change in his consciousness. This change is something that is available and has been experienced not only by Buddhists, but also Hindu's, Muslims, and Christians among others. This change can be characterized as nondual. It is the disappearance of the sense of subject relating to objects.
Bernadette Roberts' book The Experience of No Self is a very good introduction to this as she writes as a contemporary American. Her background was years spent as a contemplative nun before leaving to be a mother and householder. She remains Christian but did state that when she read some accounts of things the Buddha said she recognized at last some one else who had experienced what she had.
Wayne Liquorman's book The Acceptance of What Is is also a good contemporary American account of the Hindu advaita (non dual) teachings.
Googling on those two names would get you a little on them to start. Both of their books are in my local library so you should be able to find them or get them through an intra library loan.
Bear in mind that no one is enlightened. An individual can be said to awaken but that awakening is to the realization that there are no separate individual beings. This is one teaching of the Buddha:
In reality there is no such thing as an I who liberates, and no other who is liberated. If a Bodhisattva holds on to the idea that a self, person, living being, or life span exists, that person is not a true Bodhisattva!"
http://www.spiritual-happiness.com/nlpupdate3.html
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