Lots of interesting opinions from folks here on building science and theory.
I will throw a suggestion in here about insulation. Your best bet would be to find a local reputable building scientist to come up with a thermal boundary/insulation plan. There are benefits and drawbacks to each type of insulation. Even fiberglass is a cost effective insulator as long as there is absolutely no air movement through it. I won't give any specific recommendations because I know my environment and professional building practices for cold/snowy northern climates. These practices would be completely different from the practices in your area.
So I would look up someone in your area that is BPI certified and have them help you out with insulation and air sealing for the house. In the long run this will save you money and energy. Also a properly detailed insulation plan will also make the rest of the house last a lot longer in terms of addressing roof temperature, air management, moisture management, etc etc.
all the systems in the house are connected and need to work well with each other.
Very good points by nctacoma...
Also if you read the article attached and its side tabs, you will see that there is a lot more " make the numbers sell the products" than actual reality in the environment and way we live.
Calculating heat loss