Helen, you have performed an excellent experiment, and there will be fewer frostbitten ears next winter because of it. On behalf of those ears, I THANK YOU!
To help myself replicate your versions of this ingeniously designed hat, I've put your photos and information into a one-page PDF, and to help others, I've attached it below.
When I made these I was not fussy about what size they turned out as they are all for charity. I figured there is always a needy head for any size hat.
It was quite interesting to see the difference in size just changing yarn and needle size. I really love this pattern.