You know why this issue is so important to our Christian friends?
Because Paul told them that if Jesus didn't raise from the dead then their preaching is in vain, or something along the lines.
For us, we don't care whether that was spiritual death, the soul left the body or the whole body, etc which appeared in all your arguments and the others and none of it has any solid proof. Therefore, we say that Allah knows best and he will tell us all about it in the after life.
What we know for sure that even if Jesus himself was here, he would just be a Muslim, and if he was there while prophet Mohammed was there, he would have no choice but to follow prophet Mohammed "peace be upon him" because it's not about who was greater, but about the plan of this message of God, and his orders.
Well, I wouldn't consider taking a blind leap of faith as proof that Gabriel spoke to Mohammed though.