Trail of Blood is a good book, but you have to be careful about some of his claims. Some of them can not be verified today. Some of them aren’t clarified enough and can lead to Baptists being linked with some heretical groups as well.
I agree to a large extent. I once had a pastor who promoted the booklet. I mentioned to him that some of the groups that “Trail” lists as Baptist were people who would not be welcome in his church. Tongue-talkers, for instance.