Today I apparently snagged the derailleur (X9) and snapped the cage which was plastic. Is there a noticeable and worthy difference between the X9 and X7 short cage derailleurs? The X7 is a little cheaper and from what little info I can find seems to perform about the same. If weight is the only difference then it's a no brainier as I only ride DH, the cheaper would suffice as a disposable part as long as the performance is up to par.