I'm having a 7 SAUM built on a Pierce short action(been waiting 14mo so far) if I could do it over again I would use a Defiance action(smooth) and a smith from here.
My 7 SAUM has a Surgeon 591 and I love it. I'm planing a build on a 1581 next. I absolutely love the Surgeon actions and it would take a lot to change my mind. The way I see it, you can't go wrong with a Surgeon.
I would go with the Defiance. The AW mags will not feed the WSM or SUAM cases, so there won't be a need for that type of magcut. I generally use the Badger cut on my WSM builds on our action that Defiance makes for us. This allows the use of the WSM Accurate mags and either Badger or the even better, new Seekins AI bottom metal. The RSR's are nice as well, but the Defiane actions are among the smoothest out there.....kinda partial to them as they make our action for us and are close friends.