1 sided cord is superb when you're using headphones in bed. just throw the cord above your head and forget the headphones.
every full sized headphone will change their sound once you add pressure on one cup by laying on the side. not mentioning that this is hardly a solution.
i can approve that the HD600 are easy to fall asleep with. something is magical about the HD600 at low volumes. if you buy these, you'll remove them sometime later in the night, nothing to worry about too much. build quality is just fine. otoh, the cord ain't one sided.
ER-4 are dangerous. i'll never go to bed with them. i might wake into the worst day of my life. the stick out too much from the ear.
don't know about shures, still haven't met my E5, which are waiting for me abroad.
Lindrone,
you are our test dummy now, you must go and sleep with your E5 for a week and report if any eardrum damage done!