Looks great felted, though! I've never done this to double-knitting -- I like the stitch definition too much. Kudos for trying it!
I've made 5 more of these hats as there are allot of missionaries in my church. All with VERY different size heads. I can say I have mastered the sizing problem without messing with the main design. I finally made one my husband loves. He does not care for the felting aspect of my sizing method, but others LOVED it.