The Five is the basic brake in the Avid family, without the Speed Dial bite point adjustment of the Seven and its friends, but it's still a great XC anchor.
The unique steep angled Power Reserve Geometry lever gives a consistent pull in line with your natural finger movement for a genuinely 'power assisted' feel.
Masses of one-finger power and very rich feedback at all pull pressures makes the 160mm rotor more than ample for most XC applications , while the 185mm is comparable to most 200mm-plus brakes. The actual 203mm will throw you like a siege engine, although dyno testing and some mountain use show a sudden rather than gradual failure at high temperatures. However, the new Code DH brake should have that sorted.
The cup and cone CPS positioning system and two-piece lever clamp make installation easy, and pad life is excellent, too - although bleeding is awkward without Avid's syringe kit. Weight is only average, but the 'dislocating' lever helps brake and knees in crashes and the new pricing is excellent for the feel and power.