IN ADDITION:
I just remembered, another book which might be of interest to several forumers here…
This is back from the days of the old Misnagdim. One Chossid of the Tzemach Tzedek (and I think he was the chossid all the way back to the Alter Rebbe, if I’m not mistaken) who was challenged by a very serious Talmid Chochom who was a misnaged, regarding several questions on Chassidim. One of the main questions was one of the change of Minhagim.
Well, what ensued was a sort of debate which was printed in a book in recent years called “Vikucha Rabba” ויכוחה רבה, which is fairly in-depth, on the matter…