We're getting into building envelope issues. Are we relying on the styrofoam to create vapour barrier seals acknowledging the 1/3 2/3 rule of vapour barrier placement? This would imply the taped seal on the inner face, which is impossible to do, with the wrap and strap method, or do we have several layers of insulation? Also, the best choice method of strapping uses diagonal strapping before external siding, so any moisture that drives in can drain to the outside,, or you can cut dadoes. I've not been on the forum in quite some time,looks like a current thread, you're on the right path,, don't let me steer you wrong. I can' t see how far north you are, but we have definitely been using wrap and strap here in Peterborough. Loving the styrofoam insulation. With careful attention to polyurethane spray foam to the details. Need to think about dew point condensation. If attention is paid, you'll get a good warm house with no issues. If you rush the process, you can have mould issues.
Feel free to PM me, or we can carry on conversation here.
dave