Tom, no problem - and I fully understand. Let me explain a bit.
First things... ice dams are a roof problem only. Air sealing and insulation in the ROOF are the root of ice dam problems. And yes, there are a lot of problems in older houses in this area. You can get away with a lot more in walls, and all it affects is your heating/cooling bill.
The second issue is the type of construction.
Had you built a "typical" truss or rafter roof with blown-in or batt insulation, then you would be in a different realm. What you have is an "insulation contact roof deck" - that is different. With a typical truss roof, you blow in insulation over the ceiling and the roof deck is vented to the outside making it cool. That solves a lot of roof deck issues as there are no thermal bridges to the deck (If it is done right..). With a SIPs type roof (like you have), the issues are different. There is no vent space keeping the roof deck the same temp as outdoors. Therefore you need to keep it cool to avoid melting snow. The only way is by building a deck that is air tight and insulated enough to keep the heat in and the snow happy outside. With thermal bridges like you are showing with the panels, you will have snow melt issues, which may result in ice dam & leak problems (a lot depends on your local climate...)
You can get away with a lot more sloppy construction if you have a vented attic above your ceiling, but you do not. Even the sloppy guys there are learning it is not great to do that too... But the issue here is there is nothing between your heated living space and the outside except the insulation in the roof deck. If there are thermal bridges, they will cause problems by melting snow and making the water run down the roof.
Not sure if I am making my point, but if you held a consistent R30 or R39 then you would be fine in either case. The differential between the R39 foam and the R7 studs, is the problem. Make sense? feel free to ask more if I am not explaining it well enough...
And this is the key point - if you have ice dam problems after building, you will have to strip the shingles and lay down 1-2" of foam. How much fun will that be vs doing it now?
I am glad to see the Superior Walls worked out well. I suspected it was our local outfit that was the problem here, but I wanted to caution you to make sure you were aware.
I am impressed with your progress and really love the look of the T&G ceiling. Please don't take my comments as trying to drag you down, though I know that is easy to do. I'm trying to help by applying accepted Building Science practices here.... The envelope is the critical piece...