As a medical professional I would be particularly concerned about the type of injury that Peyton is recovering from. This is based on the following information. (No I do not have access to any information about Peyton's injury that is not available elsewhere).
1. Nerves take the longest length of time of any body tissue to heal. The chances of continuing problems from a surgically repaired nerve are significant.
2. Even repaired nerves can and most always do continue to have certain problems including but not limited to weakness of the affected area, numbness in the affected area.
3. The fact that the nerve root involved in this case involve the neck and upper spine area would cause significant concern for most people. If Peyton would be too take an awkward hit affecting the area of the repair then there is concern regarding partial paralysis. Yes that is a concern with all football players but already having surgical intervention in that area would make that type of injury more likely.
My point is that there is no guarantee that Peyton will ever be able to throw the ball like he did before and if he can there is significant chance that he could be injury prone for the remainder of his career. As a lifelong phins fan I would love to have him play in Miami but this is by no means a can't miss prospect. Be cautiously optimistic but do not sell the farm for him.