I ordered an audio-only cable from V-Moda for mine for $12US. Like you, I was using my spare from my M-100 as well. The cable I ordered is very nice and not nearly as stiff as the ones that came with the M-100. The cable that came with the X1 is quite excellent in build and appearance and, truth be told, I cannot really tell all that much of a difference - at least when I am at work. I picked up the other cable automatically because of everything I read about the "horrors" of the stock cable. Perhaps when I take them home this weekend and do some "critical" listening a difference may be heard... Just joking - I listen for fun!
cheers guys. maybe i'll just give the stock cable a go, and if i do happen to prefer the M-100 cable i'll order the audio only cable down the track (along with a boompro maybe).