Some additional thoughts: if you left industry now (or are let go by Shell later) how easy will it be to find another job based on your credentials? Do you like your current job and wish to stay in it? Making the move is a lot easier if there is the option of going back in 1-2 or even 5 years.
Does the family like Calgary? Kelowna? Happy wife, happy life
I made a similar change (pay cut for lifestyle reasons), but I always knew I could go back to the "big money" if it didn't work out or I didn't like it. In the end the choice was easy as working the "big money" job wasn't sustainable for us (we also have a young family and that was more important long term). Govt pension is also a nice perk
PS I think short term housing pain is largely irrelevant; this is a long term decision and with your current wage it sounds like you'll be able to absorb it long term.