So here's what I think helped the most in making this jump.
Training Cycle. I really think the focus on getting faster for the half in the fall, followed by a period of heavy volume with little quality in December and January, follwed by a reduction in volume but increase in quality was the key. I think this kept the training from getting too repetitive, I think the volume increase really helped in terms of overall aerobic capacity and had me ready to return to quality in the winter/spring while handling it with higher volume than last year. I still had a number of weeks in the 80s in Feb and March as well, so volume was still higher than ever leading into a marathon.
Strength. I think the focus on strength work combined with the hill work (which is not only speed work in disguise, but strength work in disguise) was critical. I never felt weak in the core during the race. And the legs, while battered, still felt strong throughout. The hills were totally manageable. I think this was key.
Multiple quality sessions.
I do think that doing 2x quality during the week is key for me. This worked going into the half an worked going into Boston. I think chosing 2 of my 3 quality workouts (tempo, interval, hill) each week really keeps all those systems fresh and keeps them all improving. Leaving one for a long period of time like Pfitz does, I just don't think that is for me.
Weight I do think getting down to my lightest racing weight ever also helped. I just felt light and strong during training and during the race. I don't think I can or should get lower than 165ish, but that seemed to be right on that line of near perfect.
Hill Climbs These are just 3-5 miles on the TM, incline ranging between 4.0 to 7.0%. Done at a 8:00 pace generally. I think these really built leg strength and made the Newton hills, all of which are relatively short (the longest is .6 of a mile) and not steeper than 5%, very manageable. For once I wasn't stuck in the sand slogging up those things.