we're in the same boat here in humid ontario. we get the best of both worlds. freezing cold. and hot and humid.
so there is considerable debate over where to put the vapour barrier.
I hope you don't mind, but I'm not the most experienced construction guy so I like to double check stuff. and there is good research out there showing that many of us are better off leaving extra breathing room on our rigid foam installs. (that's my story
the roofing install that I show in my blog comes from research I did in 2010 and is my second and improved version.
my second roof (the one illustrated) puts the air movement outside of the sheathing.
and while you put your rigid insulation between your purlins on top of the roof water proofing I used purlins or strapping over my insulation and attached the metal roof to that. interestingly that gave me the air gap now recommended.
this roof design really does remove solar heat gain very efficiently. kind of a solar chimney really.
for other people looking at this. there is research showing the metal foil covered insulation helps improve heat removal also.
you have a real nice build going there. congrats.