I own a pair of Shure E3C's, and my wife has a pair of E2C's. We love them. I wouldn't hesitate to buy them again. Excellent headphones if you can deal with in-ear phones. I would actually go so far as to compare the sound of E3C's with Axiom speakers. They share the characteristics of smooth and balanced output throughout the range. The E2C's are great too, but are a bit heavy with the bass.
I can also tell you that Shure absolutely stands behind their product. After about 18 months of heavy use one of the cords started to fray on my wife's E2C's. One call to Shure and she had a brand new pair replaced under warranty within a few days. Very satisfied wth their customer service.
Etymotic also makes lovely in-ear headphones. Many, many happy owners to be found in that camp.
I've looked and listened to the B&O ones. They look pretty and sound ok - about on par with your standard $30-$60 Sony earbuds. IMHO, they are not worth $120+. They do not compare to the Shures.
Every Apple store I've ever been in carries both Shure and Ety cans, and also have a generous return policy should you not like them.
Headphone crazies live here.
Oh, and the thing about canal phones being damaging to hearing, I don't buy it. Well-fitting canal phones will block out all of the ambient noise. Consequently, you can listen at much lower volumes than regular open-ear headphones. I've spent many afternoons listening to music at work to find that the ambient noise of my office seems quite a bit *louder* when I take them off. Kind of like when you pop your ears after having a head cold.
It is true that at a given volume level canal phones will be louder than open headphones - and that's *really* important to remember if you ever 'plug in' to someone else's MP3 player.