I need to watch that in a bit, but to answer the question myself:
At 7 years old, I'd suggest something else. He was already the oddball in his class, and sensitive to people laughing and whatnot, so I know it wouldn't have had a happy ending.
After 11.. Go for it. Actually, he did dress up like a princess for x-mas eve one year.. just to get a reaction outta his granny. Her reaction? "Oh my God look at him! So cute!" *grabs camera*