Here is my latest comment, following up on some of the comments on the previous post, about utilizing different traditions and Oro Shel Moshiach.
B"H, if your neshama is drawn to Rebbe Nachman's teachings, you shouldn't feel as if that contradicts or is disloyal to your Chabad connection up to now. For more insight into the complementary nature of Chabad and Breslov, read my translation of Rav Itchie Mayer Mordenstern on the topic here.
At the beginning of your comment, I see the main problem you have as being the "cholent" kasha. If the author were actually creating a mushkababel of different ideas into a formless, colorless, feel-good mixture, then I would agree with you. However, I believe that you are missing the key word I used (which I got from Rav Weinberger); "Unified." The seforim (and, more importantly, the Oro Shel Moshiach approach) are not a rough-shod joining of contradictory sources, but a demonstration of a higher unity that underlies different and even "contradictory" approaches to avodas Hashem.
For example, there was a bitter bitter dispute between Rav Yosef Chaim Sonenfeld and Rav Kook in pre-state E"Y. Rav Y.C. Sonenfeld held that Rav Kook's approach to teaching which exemplified this Oro Shel Moshiach approach was wrong at best, and spiritually dangerous at worst. On one occasion, Rav Sonenfeld needed some help with a help issue in his family and they required the assistance of Rav Kook. He sent his grandson, I believe, to Rav Kook's home, and when Rav Kook was sending Rav Sonenfeld's grandson on his way, he told him; "Please tell your Zaide that if he wasn't doing what he is doing, I would not be able to do what I am doing."
What you perceive as irreconcilable opposites, from a higher perspective are two necessary and complimentary components of a greater whole. Is concave the opposite of convex? Yes, but you cannot have one without the other. They are really one. Are Chochma and Bina different? Yes, but you must have both in balance and they are really one since they are both derivitives of Keser. This is also the message of Rav Kook in that ma'aseh.
You are right that we must differentiate between speculation and truth. How do we know which is which in this case? I am certainly no baki in chochmas haemes so really, I'm only basing myself on a couple of people's much-more-experet opinion in these matters. Rav Moshe Weinberger is very clear that he sees an unbelievable unity in the seforim of Bilvavi Mishkan Evneh, and that they are in no way based on personal speculation. I don't know if he wants his name announced, so I will merely say that a Tzadik and Rebbe of a Chassidus in Boro Park is of the same opinion and now has all of his Chassidim learning the Bilvavi seforim. Rav Gamliel Rabinovitch is close with the mechaber, who sees him often.
As to your valid point about the centrality of Chassidus and the derech haBaal Shem Tov to Rav Weinberger and Chassidim in general, I don't see the problem. It is true! I disagree that this is somehow contradictory to the idea of drawing light and inspiration in avodas Hashem from pre- and non-Chassidish sources. One can have their primary interest in Chassidus, like you said, and realize the truth within the other paths as well. That does not make someone an "abstract reseacher, who approaches Chassidus as 'just one more' mystical system."
I personally see Rav Weinberger and Rav Shwartz as being more connected to the way of Chochma, the way of Yosef Hatzadik. As I write in the introduction to the translation of R' Itchie Mayer Morgenstern's Kuntres, Chochma is the way of seeing the different, distinct, disperate pratei pratim and seeing the "Klal," the unified principal behind it. This is also connected to the bechina of Yosef Hatzadik. And I theorize that this is why Chanukah, which is very connected to the parshios of Yosef Hatzadik, is the Yontif to which Rav Weinberger feels the most connection.
I defninetly see your point. And that has been the derech of the gedolim. They are mechaneich their communities that their way is the way for them to follow, in no uncertain or unclear terms. But individuals can and should be encouraged to follow the pull of their neshoma to enrich thier "daled amos" with other derachim in Torah that they feel connected to.
Regarding this idea that there is great significance to that which a Jew's soul feels connected to, there is an awesome Mei Hashiloach in last week's Parsha, parshas Ki Seitzei. He places and great emphasis on the Torah's words, "V'chashka va." Cheishek is a very strong word for desire and is not be taken lightly. He explains over there based on that, that if a Jew feels a cheishek for something, even something outwardly bad, it is because there are true nekodos tovos in that thing that that person's soul needs to be mevarer, to sepperate out. How much the more so in terms of Torah! This places new meaning in the words, "L'olam yilmod adam ma shelibo chafeitz."
This is just as "A Yid" himself wrote in A Simple Jew: "If he feels attraction to certain field of study, it indicates, that this field was neglected by him in his previous gilgulim (if any), so now his neshomo arouses this urge to learn what it missed before, so the rule of "ma sheliboy chofeytz" according to mekubolim is really a deep indicator of what is missing for neshoma's tikun."
Thank you for sharing that. I know I've heard that before but I am only up to chelek beis, so you're way ahead of me. Thank you for sharing that.