Speaker Break In...? Or listener “Break In”?

Both, actually. And, it can take quite a number of hours dialing in the " sweet spot " in the room: speakers relative to the walls / corners, and the location of the speakers, relative to the listening chair. Not to mention, the acoustics of the room.

It’s not multiple choice, dudes. This is just one more example of non audiophiles thinking there are two sides to some issue or another. 

This is a very interesting topic...
Prof, very good point!
I think our listening "burns-in" probably more-so than the speakers. 
Just my opinion; but audio equipment "burns-in" quite a bit quicker than we think and/or led to believe.

In my opinion, break in is real, with speakers more than electronics. Having said that, I also believe that if you don’t like the sound of a piece of equipment out of the box, no amount of break in is going to change that. The change is small, not substantial. If it were, what manufacturer would send it out just hoping for the best?

I've heard some dramatic changes in speakers for sure - got a pair of Harbeth 40.2 a few weeks ago and although the designer claims that break in is all in your head, my experience with their 12" bass driver suggests otherwise.

Fresh out of the box the bottom end sounded really quick and had some really nice impact that I really liked.  A week and about a hundred hours later I was freaking out that they sounded thumpy and lacked definition on the bottom end.  I'm 300 hours in and the bass is tuneful and they are not thumpy or wooly at all, they follow the kick drum and bass guitar really nicely - I'm absolutely loving it.  The mids and top end sound more coherent and there is a greater overall ease to the sound there but nothing as obvious.

Just like the cable debate there are lots of differing opinions - trust your ears and if you don't enjoy the sound after you buy something and use it after a month then it's time to try something else...