That's the blog for the route from Oviedo! From the photos it looks stunning, and exhausting. On the section I looked at again they covered 12.5km in 4.5 hours, I'm going to take a guess that was more to punishing climbs than stopping to smell and admire flowers.
I like amongst the information that they give at the top of each section is the amount of dogs they have bumped into. Having bumped into quite a few Asturian dogs and the big ones are similar to the High Pyrenean dogs, that info would not be there from a purely dog lover's aspect.
View attachment 14133 This photo was taken a km after Puerto Pajares, it was tough going down from here but generally OK because most of the time you are going with the flow of the land.