Being 6'3 I haven't been friends with a girl taller than me wearing heels but it would depend on her body type. If she was overweight and unattractive I'd be intimidated. If she was attractive and had a nice figure I'd want to grapple that Amazonian princess to the ground and do the wild thing with her.
It wouldn't be a big deal to me. As long as she Isn't wearing the tallest ones possible. I Have a height preference, but never a very strong one.
However I always wondered how taller girls feel about this, if they felt strange being taller than their dates once they wear heels. Would they be less inclined to wear heels or date the particular guy?