Due to a crash, followed by a crash, followed by a hill that I tried to mash up, I'm now in the process of replacing my derailleur hanger and RD. I figured it made for a good excuse to do a bit of shifting maintenance, so I'm replacing the cables too. Is the Avid flak jacket (or FMJ) worth the extra over just running new XT cables? I wasn't particularly happy with the shifting, but that was probably mostly the fault of the x.3 RD I bought for $2 on clearance. I'd have to drill out the cable guides to let the jacket through, but it's so sandy on the trails it might be worth it - any exposed bits that move tend to get ground down by the sand in short order.