I purchased the Cardas Clear to go with my LCD-3s at the same time, but there was some lag time between receiving the LCD-3s and the Clear that Cardas had to build to order.
Honestly, I can't say I can hear a difference, and on some communities like Hydrogenaudio, if you claim you hear differences, you'd best be prepared to back it up with ABX tests, etc. or face TOS violations.
What I can say is, I feel like for $1900, the stock cable that came with the LCD-3s felt very cheap and simply did not match the quality of the LCD-3s. I feel that the Cardas Clear complements the LCD-3s better, just because they don't look or feel cheap.
Also, note that I didn't spend a lot of time actively testing both cables and comparing, but in the end I'm pleased with the Cardas Clear, because of its look, fabric jacket, and pliability. It probably does help the auditory experience, but I didn't invest the time in comparing the stock vs. the Clear, especially considering that all of the cable swappage occurred during what some would consider the burn-in period.
Could the same effects be achieved by a cheaper cable? Probably. But if you're shelling out $1900+ for a pair of headphones, you probably won't mind the additional cost of 3rd party cable.
Would I purchase the Cardas/LCD-3 combo over again? Yes.