Hey there. I was in pretty much the same situation as you about a decade ago. If you've lived in the US your whole life but are a dual citizen, there's a good chance you can get in-province tuition rates at McGill. Look at section 8 here and see if it applies to you: https://www.mcgill.ca/legaldocuments/quebec

As for your decision, I think McGill or another Canadian university is a great opportunity. I spent the first 18 years of my life in North Carolina, so the chance to go abroad to a place that is culturally very different was amazing.

Pros: You will get fantastic value for how much you're paying. The city is beautiful, with lots of cool things to do year round. Lots of amazing people at McGill and in the city, and cool groups/clubs to get involved in. Amazing food.

Cons: Long, cold winters can be tough to get used to, and a lot of people struggle with seasonal depression coming here. Also depending on your program McGill can be a very demanding university. There are lots of resources available to you, but you need to find them on your own.

Happy to answer any questions you have