Great discussion! I have a few things I've wondered about Lydiards system in the past, perhaps they could be answered here.
1) Why restrict hills to only 6 weeks (besides runs over rolling hills)? I know the workouts would vary throughout the year, but why would you not want to do hill circuits or sprints with full recovery (a la Renato), or long, say mile repeats uphill (or on flats) at say 15k-half marathon pace in base training?
2) It seems that you run at AT pace quite often (what I interpret "comfortably tired to mean), but nothing faster? Why not switch things up and do 20-30 mins at sat 5k pace plus 20 or so seconds a mile in place of one of the longer AT runs in a week? Just add to the cool down to make up for the shorter distance.
3) All running on roads? I agree about doing key workouts on a flat road, but I would think that doing other runs on grass or trails would be beneficial in that it will strehgthen certain supporting muscles not really utilized in stable footed running.