I've always been of the opinion that if you wish to study a religious text or religion, don't use 3rd party books to do so. Go to the source and read the actual holy book. Attend a service. Talk with active followers. You're never going to learn anything relying on 'ex' members and 3rd party commentary. When I was on walk-about, I attended many religious services from California to Florida and learned quite a bit.
Therein, is a part of the problem. Its the source material that is in question.
In reference to the Koran, there is no source material. Giving the fact we have a historical record of the events during which the koran was standardized and competing versions burned, the maintenance of any source material is a contradiction in terms. The completely human engine for that standard is evident and obvious. We have in our possession, at best, the musshaf of Uthman. We really do not know what the musshaf of Muhammad contained, and how different the two might be.
The percentage of Moslems that accept any particular foundational myth of Islam is hardly a basis for deciding that myth is true or not. An objective evaluation of the claim to muhammud (swish) hearing voices must be assessed with consideration to the time and circumstances.
Similarly, the Moslem myth of a perfectly preserved koran is a late development in Moslem history. The earliest Moslems did not share it as demonstrated by their own writings.