I came across some very interesting things a few days ago online.
At the Kavannah blog there was a series of posts recently consisting of interviews with a Sephardic student of Kabbalah. In the second of the posts, the talmid relates how Rav Kaduri z"l sliced out the entire Tanya , along with sichos of the Lubavitcher Rebbe, from the Chitas that he owned, after asking and obtaining permission from him to 'fix mistakes' in it.
The talmid goes on to inform us that great Sephardic mekubbalim (he names eight of them, including well known giants like the Ben Ish Chai, and Rav Kaduri, as well as other names not as well known to the general public) held that the Tanya contradicts the עץ חיים of the אר"י ז"ל (Rabbi Isaac Luria, the great, overwhelming master of Kabbalah from about five centuries ago). Also, great Sephardic mekubbalim instructed their students not to learn Chasidic sefarim!
Sometimes people assume that Sephardim and Chasidim are basically in agreement theologically. But the truth may be more complicated than that. Quite interesting.
Update: Learned from a comment at another blog that the matter is more complicated - see more here.