Welcome Eric from a fellow Vancouverite (well, North Vancouver). The rigid foam insulation does give you greater R-values in less thickness than fiberglass batt insulation, but it is heavier and it can lose insulating value if wet. The other problem I see is that it's permanent (or at least very hard to remove), so if you need to repair wiring or plumbing that gets coated with the stuff, you could be in for a real time of it. The fiberglass batt insulation will be a lot easier to work with. Fiberglass isn't the best or most high tech insulation, but it performs adequately and predictably.
Cameron & the Labradors, Kai & Samm
North Vancouver, BC
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