Russ,
I recommend reading "Metal-on-metal resurfacing of the hip in patients under the age of 55 years with osteoarthritis," by Daniel, Pynsent & McMinn. The article was published in March, 2004 and there may be updates. In a nutshell "The extremely low rate of failure in spite of the resumption of high level occupational and leisure activities provides early evidence of the suitability of this procedure for young and active patients with arthritis," and "The interim years are continuing to be problem-free and we are yet to find out when the late failures, if any, are likely to occur. Caution still needs to be exercised until longer term results are available."
Now, who is cautious? Read all of the athlete's stories on this web site. They certainly are not cautious.
My Dr. said my device was "Absolutely Perfect" after one year and to "Enjoy it." The only activitiy he doesn't recommend is running on hard surfaces. Running to catch a bus is OK, but running marathons on asphalt is not advised. I never ran much before surgery anyway, so I don't miss it. I downhill ski the steep slopes and I don't think about wiping out. I avoid skiing the double black diamonds or jumping off cliffs. I don't miss it since I didn't do that before surgery.