DMGRemember the Units!
The "total climbing" metric for my trail ride this weekend indicates just 864 vertical feet of climbing.
My copy of "Day Hikes in Ventura County", however, lists the Chumash trail as gaining 1100 feet of elevation. Motion Based calculates the elevation gained at about 2500ft, pretty close to 864 meters. And the given altitude for the city of Simi Vallye is 800-900 feet of elevation, pretty close to 300 meters. Methinks my GPS is thinking in metric. I'll confirm when I get home.
Update: I checked my GPS unit, and it's set to imperial units. So I thought that maybe the GPX spec dictates that elevation information be in meters. Yup, and fixed.