OK Goku, know that I am a spouse and that's my perspective, and am only about 8 months into even knowing NPD as a term, but I have learned MUCH here. So my view/advice from the other side is this:
-you are awesome for being here and asking such questions, so great start
-read a ton of stuff in this forum before you do anything...I agree that sharing your thoughts can rock your world, and the worlds of these other people, and seriously affect relationships and your reputation.
-If you read enough here (other people's stories, opinions and feelings) you will probably come to assume that "Non's" won't have the first clue on how to react to you if you get "real" with what you think of them, or you try to tell them about NPD even if you are focusing on explaining "you" and don't even go there regarding what you really think of them. The people in your life will probably not be able to deal with either approach, even if they care about you, without having any solid understanding on what NPD is. Only someone close to you, with a LOT of regard for you (no matter what they might hear from you), and in my opinion, a lot of experience with what you are "like" at your most honest levels you get to with people...only someone that close to you is likely to handle any NPD revelation from you. Even then, they will need a whole lot of good info on what NPD is, and (being honest here) it is probably best if you, yourself, have a solid handle on that before you would hope or expect anyone else to as well.
-Plus, I am wondering if it isn't better for you to go to a pro, as in a therapist, i.e. also a neutral yet trained stranger, to get your questions answered, and get guidance on what to do with your newfound discovery of your own NPD, if that is the correct thing you have arrived at. But, I personally don't think a lot of therapists are going to be "specializing" enough in NPD to be of any more help than just reading a lot here. And this forum is free, so a big bonus.
-If you were revealing yourself, and/or your honest thoughts about me, to me (this is a theoretical scenario with you specifically knowing me), and you were my husband, whom I love very much, and I am well versed in NPD already (I am getting there) or you did a great job of introducing NPD stuff to me, I could certainly handle you telling me you thought you had NPD...because I would already know that, or you would explain it to me well, gently, etc. if I didn't. But...a big but...even for me, now, knowing what I do now, it would be hard, and I have to assume extremely painful, and I mean really, really painful, to hear what my husband "really" thought of me, since I know from what I read here that it can be pretty devastating stuff.
-So I am saying my personal feedback on your idea is that it is full of damaging consequences, to both you and others. And I would recommend alternatives, like...
That read a lot in this forum suggestion, for starters.Get your curiosity satisfied about what it would feel like to those around you if you really told them what you think of them by reading what us Non's have experienced living with NPD partners...and how much it has hurt us all.
Maybe, Goku, look at what you think it would do for you to see people's reaction to your true opinions of them. Are you just curious? Or are you looking to find who among these people care about you enough to let you be more open? Are you really wanting to express just your negative opinions of them, which I bet you already have guessed won't go so well received, or are you kind of hoping to "be yourself" more with someone, maybe a few key people that mean a lot to you? If so, I am guessing you might be feeling tired of trying so hard to hide what you really want to say or "who you are" and are hoping you can count on some people in your life to care about you enough to let you be yourself more with them. Well, the negative things some NPD people think and would say if not holding back are generally pretty hard for anyone else to take, so I advise stepping very lightly, only with someone very important to you (and likely to adjust to new stuff coming from you), and only after you feel very well versed not just with NPD but how NPD people here interact with their own loved ones...what they feel they can say, and what they still hold back on saying.
Saying what you really think, coming from an NPD perspective, can really have devastating results for the other person. If my husband told me, for instance, that he doesn't feel deep love for me and just feels like he wants to stay married because he is fond of me, sometimes, and that is the deepest thing he ever feels, it would still hurt me very much...even though that might be the deepest thing he actually can feel, with his NPD. Yet I know to expect this, if he went 100% honest with me, because that is what others on this forum have honestly said about their own feelings for their spouses. Here I am, aware of NPD, trying to save my marriage with techniques like stepping out of my own woes and trying to put myself in his shoes, with the help of the input from the people here, and I STILL would be devastated to hear any actual words from his mouth like "I am sorry to tell you this, but I don't think I can feel love like you feel it for me...I am just giving you my best."
Even though I know that is probably the truth, I still don't want to hear it. And I am one of the "enlightened" spouses now. Just read a lot here. You will see the NPD folks who have people they care about saying they are careful, very careful, with what they say, because they know their true feelings, the most negative ones, or disappointing (to us) ones, will indeed hurt that person.
I am really sorry to say that it is probably wise to temper what you say to people...seems unfair to me too. But there is such a gap between an NPD based perspective and that of someone who has a lot of empathy (and is therefore also easily hurt) that it requires you knowing when to hold back on the most potentially hurtful stuff and your spouse (let's say) being both up on NPD and toughening up on their end for them to take some things less personally in order for you to be more honest...assuming it is a relationship you want to both save and be more honest in.
If you don't care about the other person, and still want to be more honest with them, you probably won't go to the effort of making sure they understand NPD more before you try more honesty, and your honest comments may be too harsh, if you aren't interested in presenting them gently. I don't see the results being too positive there, but at least you will get to see a reaction if that is your goal.
Good luck with what you are looking for. How to proceed (or whether to) depends on if you care about them...