[Max Minimum]

As for the health issue with the ER-4's, you'll be fine so long as you or anyone else doesn't slam something into the side of your head. I found them uncomfortable at first, but my ears quickly got used to them. I can listen for hours now and not really think about them. And, though I'm NOT suggesting you follow my lead, I'll admit that I've been anything but dilligent in even keeping the tips clean and I still have had no problems after months over wearing them approximately every other day, usually for a good two - three hours.

And here's the best thing about them in my opinion (well, the isolation is in contention here, too) is how versatile they are. Not only, as has been said, are they good for use in many environments (and saviors in loud ones), they also take VERY well to equalization or a simple turn of the bass and treble knobs. If you find them bright on a certain recording, you'll lose almost no detail by turning the treble down. You can also boost the bass a good bit and it remains tight, deep and detailed. These are excellent canalphones.

All this said, I do have a pair of Senn 590's on the way...

 

[Large4mat]

The 580's have more advantages if you are in a quiet environment---comfort, bottom end, soundstage, etc. The Ety's are great if you are in a noisy environment and need the isolation.

 

[kenyee]

Shure E3's are great when you're using public transportation (scrreeeeeeeeech.....whooooooooommm) or airplanes (rrrrrrrrrmmmmmm) though. No more covering your ears because those noises are loud enough to hurt

The HD590's sound flatter and have a nice airiness that the E3s don't...

 

[pietenkees]

If it was me in this situation id go with the 580`s. I always hate it when im totally isolated from the outside world, if im stationary. You have to stop the music for every little thing, if not take them out, cause you cant understand anything with your etys in.