3 of 5 diamonds
The tour from the trailhead at Moffat Tunnel to treeline is about three miles each way. You'll gain 2,000 feet of vert in that span, so it's not particularly strenuous—the trail gains elevation gradually, punctuated by occasional short, steep sections.
Around 11,000 feet, you'll catch sweeping views of the James Peak Wilderness, and the run possibilities are endless. Some low-angle terrain exists, but above treeline, you're mostly either in avalanche terrain or its runout, so good terrain management, rescue gear, and the knowledge to use it is essential.