I like this thread
I had been wondering about this recently myself....I do think that it can potentially overpower a person, but it just has to do with the individual.
When it comes to clothes, you want to always make sure it looks like "you're wearing the clothes" and not that "the clothes are wearing you". I think the same principle applies to hair. If you have your hair styled in a way that is fitting to you, and you carry yourself well with it, then your hair should not be overpowering to you.
ETA: Now, if you're very short and your hair is hip-length or longer, I will say that the potential of your hair overpowering you (regardless of how it's style) is greatly increased....