I just have to chime in on these buds. I came very late to this party, but I'm glad I did. An amazingly fun and engaging cheap thrill! I had several brands of earbuds from a few years ago, and settled on the good old Sony MDRE828LP for durability, convenience, and acceptable sound. Never really wanted to use them much, always preferring my SR80 phones at home. But the PK3s have changed my mind about what earbuds can sound like - actually like real headphones. Not quite Grado sound, but still fun, good for all kinds of music. You have to get a decent fit, though, and I settled on using one bud with cable wrapped over ear, the other down. Works well for me.
I don't want to know how first-ear how much better other earbuds can sound; it would be a wallet-mugging.
So far no problems with durability at all. So far.
Now I have to give IEMs another chance. The PK3 is so inspiring!
Glad that you like them. The PK2 are even better (at least I think so).
There are other good earbuds and you can get the best ones for around $200 (unless you try to get vintage Sony and Aiwa earbuds). You might not get as much bass with earbuds as with IEM's, but you get a much bigger and deeper soundstage.
You can check these threads out: