The Obsidians are indeed merino. I wore them for the first half of last year's archery elk and if the weren't complete MC Hammer pants, I would still own them - I don't have huge calves but they were fairly tight around mine and super baggy through the crotch, waist and butt. They did keep me more comfortable in a wide array of weather than the Kanabs and their breathability was amazing. I can't speak to the Corrugates, I've never owned a pair.