Trail running is great! The dirt is a nicer surface, the scenery is better and there's shade so it's not as hot. Plus it's fun to dodge the rocks/roots and zigzag around the curves. I did a trail run yesterday and a road run tonight, and I think even my form is better on the trail than the road; I didn't feel exactly graceful tonight as I ran down the steepest hill on my route! I just go by time rather than distance on trail runs--it's easier that way. I suppose I could sit down and figure out the distance for the section of the Midstate Trail that I often run on.
2011 Surly LHT
1995 Trek 830