I was thinking about this a bit for you.
The downsides of Hawaii Island is that it is expensive to get a house, the can be educational challenges, if you need any serious medical attention you may need to go to another island. It's far from relatives who live on mainland.
There is a place here called NELHA. You could look into that. With your background you could probably find employment there.
The only way to get any kind of deal on a house here is to build a simple one and be very hands on in the building process. Other than that everything is Old and overpriced. Even then it can be expensive depending on the cost of the land.
But other than the House or Rent, cost of living isn't very different from other places I've lived. Also we spend very little on Groceries.. I guess if you want to come here and drink a gallon of milk every day, but my friends who do that own cows. I don't drive very far, spend little on gas. This includes boating.. only need to go 3 miles to get to the Tuna Grounds. I guess some people get Island fever, but I still haven't been to 90% of this island and just barely make it through each day with the kids. Ofcourse there are some downsides like every where. the biggest challenge for us will be schooling, the Public Junior High and High Schools you need to make sure your kids are on the right track and be involved. There are private and Charter school options.
One thing my wife loves about this place is that Hawaii is Asian. Her words. And it is. 70% of the people in Hawaii are Asian. 15% are Native Hawaiian. 15% are White. She feels very at home here. Something I never really thought much about. I've been in the majority growing up in USA, but also in the minority living in the Village in Indonesia for 20+ years.
The way it works is if you can work and your wife can work.. it is a big step. It is a cultural change. Some people it doesn't work out. We are pretty happy. It would be tough to go back to dreadful winters and big population centers.