Let's talk "burn-in".

So it's a controversial topic... whether the "burning in" or wearing in of speakers/headphones and other audio devices is really a factor in their frequency response.
I lie on the side that certain specific models and brands of audio devices do benefit from some "burning in". Maybe it's just my ears getting used to a headset's sound... but usually after maybe 5hrs of sound they're usually a bit bassier and less bright.

So my questions to you guys are
1. Do you believe in the audio "burn in" hype?
2. For the "yes"-answers, do you think that burning in using reference material containing heavily different frequency content can result in a different sound signature (that is, the let's say two of the same speaker, one burned in with something very bright with little bass and another with something bass-heavy)

Any other thoughts? I think it's an interesting concept. The logical part of the "burn in" concept lies in that it seems to make sense that the materials and components are going to sound different after they've worn in, moved around a bit after being in the factory - tested, even?

The manual that came with my Focals said to burn them in for a certain amount of hours. It may have opened them up some. I can't really remember.