As for my take: The X5s and X10s sound similar, but not exactly alike. The X10s, as I mentioned before, provide stentorian bass. The X5s don't reach as low, but let you hear deep bass nonetheless.
As for the midrange tones (where most voice and music exist) it's a pretty close tie. The X10s might be just slightly more accurate in frequency response -- but the X5s are almost their equal -- and in some cases provide a little more punch and a subtle detail boost to voices, brass and woodwinds.
As for the highs (cymbals, and overall airiness of sound), it's close to a dead heat, with the X5s being a tiny bit more extended.
The X5s sound fantastic after only 100 hours or so of use. I've found that Klipsch headphones sound their best after a few weeks of use and breaking-in -- the treble smoothes out and becomes even more extended.
As for comfort, there's none better. I find I can keep Klipsch headphones in place longer than any others I've ever used -- and believe me, after an hour ride to work (each way) on a New York City subway -- comfort is just as important as sound quality to me. It probably is to you, too.
If you primarily listen to the best-quality, uncompressed portable music files (WAV or Lossless formats), I would go with the X10s. If you prefer lesser-quality compressed files (Windows Media, iTunes, MP3) the X5s might be a better choice.
The new Klipsch Image X5s come with a carrying pouch, a two-prong airline adapter, five sets of different-sized ear gels, and a cleaning tool. X5s have a retail price of $249.99 and will be available at select retail locations and klipsch.com. As a bonus, purchasers who complete an online warranty registration will receive a free package of replacement Contour Ear Gels in the size of their choice.
The X10s, and now the X5s, are highly recommended.