All of my Gustins have shrunk at least 1" (from a 34.5" inseam to a 33.5" inseam) with an initial warm soak and hang dry. I'm glad I do it before sending them in for alterations.
Also certain fabrics do shrink much more than others. Case in point - the Slub Browns - which are super small (comparative to other Gustin jeans) to begin with, also shrink an exceptional amount after warm soak and dry. So just be careful..