Unfortunately, I cannot offer any guidance on your particular situation given that it is a situation I have never even tangentially experienced. However, I wanted to say that your questions / reservations do not at all seem anxious. In fact, everything you’ve mentioned in your post sounds prudent to this life altering decision. Good for you for acknowledging the complicating factors (as opposed to overlooking them, like most).
The only general advice I can offer is that your instincts to maintain bridges are spot on. In my line of work, it’s called “playing nice in the sandbox.” And where possible I’ve found it of great benefit to leave places of employ on good terms.
I wish you all the best and hope the council you receive (from this site or otherwise) leads you to the best decision for you and your family. Best of luck!
“Endless amounts of free pizza” makes UBC a no-brainer choice, IMHO. My school only has free beef burger once a year.
But seriously, the extra cost is something to consider if your estimation is correct. 50k is not an insignificant amount. The dual degree program offered by UBC is with HKU (maybe Beijing as well?), it’s for students who want to practice in HK. Cantonese is a must if one wants to really assimilate, and the tuition is very high.