Not that I have much experience, but if you can do it affordably, why not? I would imagine it would still be illuminating somehow, with all of the subtest info, more than just the one number. Do you think he's 2e in any way?
Also, I just recently brought up the whole giftedness subject with my mom and found out, much to my surprise, that I had been tested through my school in K and 1st, and even more surprising, that she still had my results despite our many moves. I found the information interesting (although I wish my mom had acted on it instead of just filing it away!). I would guess that your son is more informed about his giftedness than I ever was, but perhaps when he is an adult, he will still be looking for more info about himself, and you can offer him the results... just a thought.
I also sent you a PM.