I'm a Qur'anist and I have been since I converted. We pray but our prayers aren't formal and we don't have to use Arabic, no convert Qur'anist I've ever known can recite Surah Al-Fatihah. That being said we do know the complexities of Arabic from the few of us who speak Fus-ha, or classical Arabic. Apparently Jahilli (Pre-Islamic) literature doesn't even always take the term salat to mean prayer, its roots being to follow something closely. Also the Hadith and especially the Sirah are probably accurate, but if you look at stories like the biography of Abdullah Ibn Salam (A converted Jewish Sahabi, or companion of the prophet, basically the first community to recieve the Qur'an) what he says doesn't really correspond to Rabbinic orthodoxy even at the time of Muhammad, which lends credence to the statement by God that the Jews of Muhammad's area around Mecca considered Ezra to be the son of God as the Christians believe of Jesus. They were probably of a small offshoot branch of rabbinic Judaism in Arabia that has long been extinct, whether you believe in the historical narrative of divine revelation, inspiration, or that he simply wrote it. I lean towards the first option. That being said, God's statements about Christianity may have been regarding some sect in Arabia as well, as they really don't fit with Christian Orthodoxy. It seems that Muhammad, baffled by these contradictory realities and certain of his experiences, may have concocted a conspiracy theory out of a single verse of the Qur'an in Surah Al-Bahkara 79:
"Therefore woe be unto those who write the Scripture with their hands and then say, "This is from Allah," that they may purchase a small gain therewith. Woe unto them for that their hands have written, and woe unto them for that they earn thereby."
This theory took root in the Muslim community, the idea of corruption in prior scriptures is so complete and deeply rooted in Muslim identity, that they will simultaneously demand acceptance by Qur'anists of the Chain of narration of Hadith, or Isnad, and reject the chain of apostolic succession and even the line of descent from Aaron as holders of accurate traditions. That is not to say that Islam is stupid, not even the most orthodox, blunt and straightforward interpreters of Islamic scripture and tradition are unaware of philosophical arguments for the existence and necessity of God as they see Him. Still, sects like the Muttazila were far more successful in forming coherent forms of theology than modern or classical scholars of Islam.
All this is to say that yes, I am Muslim, but I get takfired every time I say so to an Orthodox Muslim as I feel free to disagree with the prophet on religion and with God if I deem His actions to be evil, for instance I would openly serve Satan before I refuted all of the philisophical advances in morality of the Western Enlightenment and threw a gay man off of a tower because he acted out in public.
Akhi I've gotten to trade E-mails with Tovia Singer before.