For those of you who have insulated between the roof ribs with rigid foam, and subsequently added through-roof features down the road (more vents, skylights, holes for solar power cables, etc.), you are likely to have decent insight on it's mechanical performance.
1) Have you noticed any issues with the foam staying put?
2) How much time and miles had passed since initial install?
3)What adhesives or methods did you use to keep the foam from shifting or settling?
4) Did you fill the cavities entirely, or provide a gap for a radiant barrier?
5) What would you do differently, given the knowledge you have about the products and methods you chose, a similar time frame to install, and 150% of the budget you spent?
6)Would rockwool solve any of your problems?