Not unique to Alaska's, by any means.Leather bootee or plastic, molded soles or Norwegian welted, Vibram or otherwise... there have always been variances in sole thickness, duckbill length, and duckbill grinds. At least in the last 25 or so years that I've been observing it.
Starting to sound though like the Alaska's may be more inconsistent in their inconsistencies (as far as sole thickness)?
Whatever they are, I'm glad I can still use 'em in my Chouinard, Voile, and Burnt Mtn 3 pins. They're just so damn warm and cozy, it makes up for the soft and variable soles.