Hi, Vacajoe,
I was walking this spring when you posted this, so I am a little late with this question. I am helping a friend plan a Camino Aragonés and have done enough research to know that she definitely should do the Lumbier gorge alternative from Sangüesa to Monreal. Looks like it adds about 5 km. But what I’m not clear about is your stop in Yesa. That must be off-Camino, no? Did you go there from the gorge? Did your route include a detour to the Monastery at Leyre on the other side of the reservoir?
When I walked the Aragonés a few years ago, we somehow missed the Lumbier gorge
and also got advice that heading to the north of the reservoir to go to the monastery was complicated. I visited the monastery and slept in their hospedaría years ago, but loved it so much I am sorry I didn’t go back.
Thanks, buen camino, Laurie
P.s. And I also see from @caminka’s post that there are alternative ways to walk the gorge. Do you know anything about that?