Wally can give you a good review of his SOA in the rear. From what I've seen and heard from others, it works well but can give you some big pucker factor in off camber situations. I guess it's how the SOA is done and there seems to be a wide range of lifts that can be achieved. Jim Real's 40 has a nice SOA that sits low and does not pitch and roll like most SOA's. There's also axle wrap to contend with that comes with SOA.
I'd stay SUA keeping the center of gravity down and being better planted in the rocks and in off camber stuff. But, what do I know.
Will the 40 be a DD, trail rig, or both?