PMD has 3 well defined sections, as follows:
Upper-Upper: From the top down to the atmospheric research station road. This is the most technical section, and can be wet in the early season or after extended rains. If it's been raining a lot, start at Middle Upper by picking the trail up at the research station road (see below). Lots of Ups and downs on this stretch, but more downs than up - expect to pedal a bit while clearing the rougher spots.
Middle-Upper: From the Research station road down to where PMD intersects Marble Mountain
trail is awesome natural singletrack. The trail dips and rolls down the mountain, with little need to pedal. Most folks find it difficult to ride this section without smiling. Also very difficult not to ride this section fast. Heads up for hikers, and heads up for a couple deep water-bars shortly after crossing the road from Upper-Upper.
Lower: Below the Marble Mountain
trail, PMD has a couple short rocky sections, but it's 95% smooth and fast, with only minimal pedaling necessary. The last 1/2 mile is on private property where it's very important to stay on the trail. Be sure to follow the signs and exit the woods at Up a Creek restaurant, where they have kindly allowed trail users to park a car while riding the trail.
Bring two cars to shuttle, haggle with the bike shop at Up a Creek for a ride (shop planned for summer 2014), or the town of Wilmington provides shuttles for a few hours every other Sunday starting in June and running through the summer for 5 bucks. Of course you can always just pedal back up to your car too because you know, Enduro.