I invested in the Klipsch X10i/X11i/X12i earbud a little over 3 years ago. I say "invested" because these babies go for over $400 after you include tax.
It was a tough decision because of the price and I was really nervous about buying something that expensive without being able to check it out first.
I would generally assume that anyone that would spend that kind of money on earbuds to be a major audiophile who has a need for acoustic perfection. I do not fit that description at all!
My purchase decision was based mostly on the shape of the earbuds themselves. The Klipsch X10i is the only earbud on the market that comfortably sits inside of my motorcycle helmet.
Now that I have used these buds for a long enough period of time, I don't know how I ever lived without them! From a sound perspective, they are far and away the best that I have ever heard, leaving both the standard and upgraded buds that are available from Apple in the dust. They also leave my 3-year-old Shure buds behind when it comes to depth of bass.
The most impressive thing about these buds is the incredible range of individual instruments that I can now pick out. It's like listening to music again for the first time with almost my entire collection!
There are other inherent benefits to the shape as well. First, the choice to make the rubber tips oval instead of the usual round shape makes for a significantly more comfortable fit for long term use and noise elimination. Second, the lay flat design doesn't just fit a helmet, it allows for relatively comfortable use with the ear buried in a pillow. That means I can lie on my side to watch a movie on my iPhone as I'm falling asleep!
Overall, if you have the means, I highly recommend this product.