My comment on the aging of buzzards is indeed a demonstation that one should read the complete account and not just the "Age" bit. But I think this will not happen in the field. Having ringed and measured the bird, the ringer wants to put an age-class on the captured bird. He will skip directly to the age paragraph. I think it is the best policy to put the best usable feature first. I always use the primary moult pattern first and use the plumage pattern with care in (mainly light patterned) buzzards.
And yes, I consider the book for what it was designed for – [in my view more than] a general ringer’s reference field guide for Western Europe. And I will use it as such. Great work!