Smidge, I would venture to guess that more information is always better than less. But particularly with a profoundly gifted child, you may want to be leery of misdiagnosis. It could simply be that he is having difficulty contending with all the sensory input, particularly if he is processing it all at a much deeper level than most 4 year olds. And he may be struggling with overexcitabilities, rather than showing signs of ASD or Asperger's. Have you read about Dabrowski's theories?
Re crowds and the noise that comes with them: I still sometimes have to exit such situations quickly because the noise and other stimuli can make me absolutely crazy. I can't imagine how that would feel to a 4 year old.
Good luck sorting it out.
