My wife has the "touch of death" with just about everything, if it can break, she will break it (I'm not sure how I've even lasted twelve years!). When I want to test the durability of something, especially electronics, I give it to her. We pre-ordered iPhone 4s', I still have my pre-ordered 32gb...she's had 14.
I gave her a set of S4i's that I had that were no longer in my rotation. She doesn't care about anything "hifi" just size, looks, and a mic. She was amazed at how good they sounded (easy to do in this case) and has had them for about two months now. So far the dog has lightly chewed the left bud, the cord was shut a few times in the glove box door, I found them in the bathtub (no water in the tub, but who knows?!?!), she left them plugged into a treadmill at the gym for three day (how they were still there I will never know), and I cringe every time she takes them out of her ears...she yanks them out about half way down the cord!!!
I feel bad for them honestly. But, the only visible damage is from where the dog chewed them a little...a couple little teeth dents. I put them in yesterday and they still work, even the mic and controls.
Maybe they are the exception? She had to have a set of beats when they came out because it was "cool" at the gym...pulled the wire right out of a bud in eight days. Four or five sets of Sony EX58's...all broken in days. And, a slew of chain store buds from $9-$100 or whatever looked pretty that day. I'm pretty impressed that these have lasted this long...two months of her abuse is like two years to the normal human being. So, I have to say our experience has been pretty good with the S4i.
Also, they do make the "rugged" version that is supposedly sweat/water resistant and apparently more of a robust build. I did read somewhere though that the sound quality is a bit different. I never really cared for their SQ to begin with, but just a suggestion.