This relates mainly to Jacob's opening remarks. I composed most of this before reading the contributions from daylen and 7, who wonderfully express many relevant points already in their own unique ways.
Just to establish some rudimentary terms, lets differentiate between the unitive mind, the mindful mind or mindfulness, and the standard "monkey brain".
I would distinguish between concentration (being able to hold attention on breath for X minutes) and mindfulness which is more "choiceless awareness". Generally, you need a well-developed concentration to be able to proceed into mindfulness.
In a Goenka retreat for instance, you do multiple days focused exclusively on "anapana sati" (concentration on breath in the nostril area) followed by multiple days which focus on increasing mindfulness of the body ("body scan"). Similar to the transition from concentration from concentration to mindfulness, you probably need some degree of mindfulness to proceed into unitive states. For various reasons people are able to skip along the C->M->U progression.
There's also controversy in Buddhism on whether you should explore the so-called Jhanas (which for the purposes of discussion I consider to be the same as unitive state) or go straight down the mindfulness path all the way to "enlightenment" (whatever that is, I don't think unitive states are identical to it). My sense here is that the Jhanas are actually quite useful stations along the way, at least for some people. In fact, they might be the whole "path" for some.
I like the MTCTB book by Daniel Ingram for thinking about spiritual maps from a Buddhist perspective. He discusses the Jhanas in some detail, as well as various stages of mindfulness:
https://www.mctb.org/wp-content/uploads ... _Final.pdf
Does this mean that on an individual basis, a unitive state/perspective does not bring about anything beyond a sense or feeling of being content ("everything is right and wonderful and just how it's supposed to be. It's all part of the one.")
I feel like I need a lot of disclaimers up front. I want to say that I'm only basing this on my personal experience and intellectualizing on what happened. I never went to a formal teacher for guidance on it, although I did have some support in a spiritual community when it was shared. It's important to note that my conception of unitive state likely reflects something quite commonplace that is resonant to many other people including some on this forum, although perhaps the duration and frequency differs somewhat from normal(1). It may also be reflective of some kind of clinical disorder. I do feel a sense of reverence and awe that makes me want to be careful talking about these things in any fixed way. I also feel uncomfortable using first-person language to describe unitive states at all, but I see it’s more of a convention towards better understanding. I don't feel particularly attached to the label unitive state, and I could just call it "a powerful form of experience that changes how I view reality in some way that is meaningful and useful for me."
Each person’s experience of unitive states will be unique. It’s like drinking the perfect cocktail tailor-made for your own life situation. I also get the sense that there are multiple gradations on unitive consciousness, and that I am dipping my toes in the shallow water rather than swimming in the much deeper ocean. The early Jhanas have some similarities to the unitive state that I've experienced. The deeper (formless) Jhanas are maybe something that I might have touched for a few moments, but they are far less stable.
I think unitive mode brings you something even at the N=1 level. One thing it might do is to bring all levels of personality into synergistic operation(2). So if you're INTJ, your ESFP shadow might play a nearly equal role in your day to day experience. When I am in a unitive state, the "world of feelings" becomes real and tangible, rather than something that is intellectualized and inferred (which is my usual mode of operation (3)). I can suddenly visualize the “structure” of people’s feelings similarly to how in I can (in normal mode) often see the structure of people’s thoughts when having conversations. This manifests as a strange form of synesthesia that is based on “feeling tones” as well as being able to anticipate what people are about to say remarkably well. I am more externally expressive than normal, if I feel the need to be (4). Similarly, the "world of sensation" (both Si+Se) becomes significantly heightened. I could stare at a flower on the side of a trail for hours on end. (But that might not be appropriate because I would have a strong, almost deterministic sense of purpose as to what needs to be done in the moment). Normal conservation with others goes from trying to efficiently determine truth or falsity / good or bad (generally what I focus on in normal mode) to something far more multi-dimensional. Individual words have their intended meanings for sure and I am able to understand the message, but the full set of associations / overtones are equally accessible in consciousness in a playful way. Compassion for everyone becomes salient as a profound knowing of a being on a thinking and feeling level which is coupled with appropriate action to help them (if that's actually needed in the situation). You become an instrument of the Universe for the present moment in global history, while realizing that everyone else is also an instrument, so nothing special. For this purpose, you get more tools in the toolbox at the personality level and can better address whatever life throws your way, even as N=1 player.
David Hawkin's book resonated with me after a multi-day experience of unitive states:
https://www.amazon.com/Eye-Which-Nothin ... 140194504X
His lasted a lot longer than mine (permanently?). I am not sure exactly what he ended up doing with his unitive state exactly. I think that he continued his practice as a doctor, as well as making some visionary contributions to his field (after a "career break" spending some time as a hermit trying to integrate his experiences). I do get the sense that after his unitive experience he might have gotten caught up in some fields that are close to pseudoscience, but he does seem to have some recognition from mainstream bodies for consensus reality contributions. I did not look into his relationship / romantic conduct, which I do think is relevant to the validity of his claims (see (4)). I think what you “do” with unitive state (level of impact) is based, to some degree, on your skills and capital going into it.
I want to say that I do not think that having access to unitive states prevents you from going down some strange paths that are not globally true/good/beautiful. Of course, the same can be said for mindfulness (kamikaze pilots?) and clearly for ordinary monkey mind.
(1) I am not sure how frequent unitive experiences actually are in the overall population. I get the impression that many people (perhaps not a majority) have had them for short periods , sometimes only a couple of minutes. 49% of US population have had a “mystical experience” according to Pew Research(5). Having long duration experiences is probably relatively rare by an order of magnitude, and "living the unitive" is rarer still. NDEs and psychedelic drug usage seem like two frequent catalyzers. Sex and meditation are a few contributing factors that I’ve seen mentioned. For me - meditation, diet, and exercise bring unitive states on if combined in just the right way, although not reliably.
(2) There are some things about the unitive state that do not find so easily under a personality lens, but I am still wondering how to effectively describe them to others. I feel like the personality frame is more tangible. For example, there seems to be a surprising increase in the frequency of synchronicities that creates some interesting and challenging situations. At certain points, time seems to be slow down rather profoundly, and you feel like you are in eternity.
(3) My thought processes are usually still intact throughout the unitive state and not muddled. For instance, I was able to perform well as "standard office job" duties even while in the middle of a unitive state that lasted multiple workdays. Obviously there is some cognitive load needed towards appropriate masking if you're not in a good environment, but that comes with the territory I think and could be obviated with solitude or supportive community. It's also possible that especially for the first few times coming into unitive states it takes the mind some time to adjust to the new situation where other personality factors are coming online.
(4) As the relatively cold-blooded INtj male that I am, yes, even I have fallen in love before with another person before.

Unitive state feels felt more falling in love with everyone at once. But not in a creepy or possessive way. It has sexual elements but includes other aspects as well. And it doesn’t have the same “bubbly” nature. It seemed more detached and aloof, while also engaged. I realize that the term falling in love might mean different things to different people.
(5)
https://www.pewresearch.org/short-reads ... periences/