Ibn Warraq is a valuable voice in the discussion, but his credentials have been questioned.
There needs to be a multi-author, peer-reviewed published study.
I have read the such is under way - perhaps more than one - but have no details on participants, sources or status.
Aren’t his credentials difficult to verify one way or the other since he writes pseudonymously?
Another comment on Ibn Waraq. The book I linked to through Amazon- The Hidden Origins of Islam, the German editors quote Waraq extensively.