I'd get the Avid Flak Jackets. The XTR cables aren't worth it IMO, especially if you have sections of exposed cable. Save your money buy some standard housing and some stainless steel cable.
You'll spend $30 for the XTR. (Sold as singles, you need two), the Avid's are sold as a set (front AND rear included) or buy some housing (about $1/ft) and two sets of stainless steel cable ($4 - $4.50 ea). Figure 10 - 12 feet of housing for a bike front and rear with some housing left over.
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