Personally, I accept that grading given by Maulana Haroon Abasoomar, as, in South Africa, he is regarded as one of the `Ulamaa who are most knowledgeable in the field of Jarh wat-Ta`deel (The Science of Discrediting and Endorsement, also called "The Science of Narrator Criticism"). However, another famous Aalim from SA disagrees with his view and actually wrote two books refuting this view, and that is Maulana A.S. Desai (Mujlisul Ulama of South Africa), and those books can be downloaded from here:
Part One:
http://www.themajlis.co.za/books/Rai...4PRINT_PT1.pdf
Part Two:
http://www.themajlis.co.za/books/Rai...0_part%202.pdf
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You can read that just to get another Aalim's perspective on the issue. But again, personally, the view that I agree with in this regard is that of Maulana Haroon Abasoomar, because
Jarh wat-Ta`deel (The Science of Discrediting and Endorsement) is his speciality, as is
`Ilm ar-Rijaal (The Science of Biographical Evaluation).
والله تعالى أعلم
والسلام