It's cooler here in Florida now and I've been training for the Town of Celebration Marathon coming up on January 26. I've stepped up my road and trail running and am aiming for a PR of 4:30 there. The course is a double loop, very flat, and is a Boston Marathon Qualifier; for my age, that is 3:50 so I'm not even close. On December 21, I did my fastest trail run, 14.45 miles with 10:30 mile splits and early Christmas morning, I ran my fastest 5.5 mile road loop in the park (with hills) in 49:55, translating to 9:05 mile splits.
I found another book about triathlon called Faster by Jim Gourley. Lots of practical information and advice on how not to spend money on things which will not improve your speed. He found that on the bike, an aero helmet has more benefit than aero wheels and an aero frame has little benefit at all. A properly positioned rider is the best aerodynamically. He also found that trail running is 43% harder than road running, a notion I agree with.