oops, sorry, didnt see that. I'm terrible with names so the name of it in your post didnt mean a thing, and I obviously missed the Oregon mention.
Re sizing, this touches on the importance of physically trying on things, I'm a skinny guy and from one brand to another of X clothing, a medium can be ok, or I can be swimming in it. Same with rain pants, some are just so billowy on me its terrible. I found a pair of North Face rain pants that work well for me, but as you say, if sizes vary even between models, then you really have to try them on.