First of all, the Glaistig hat. I, and several other women I managed to get my hands on this weekend, all tried on both versions of the hat many, many times, and came to decisions about which hat is better. Both hats fit everyone, since the fabric is very stretchy.
For myself (22.5" head), I am almost completely undecided. The hats have a slightly different fabric to them, and I am leaning slightly toward the more tightly-knit one. On the 8's. Yes, another reversal.
Most of the women had smaller heads than I do, and they all strongly preferred the 8 hat. Two of the women had larger heads, and they both preferred the 9 hat. So, what I've decided to do is say 8 for the pattern, noting that if you have an especially large head you might want to go up a needle size.
Secondly, the hat experiment was a success! I finished the knitting last week, and this weekend did a quick-and-dirty temporary version of the finishing just to see how it looked and I love it! I will post photos of the hat later this week after I do the real finishing. I will also write up the pattern. I'm going to be putting a lot of effort into this pattern - the finishing is complicated (324 stitches around on a size 7 needle - it doesn't exactly sit on my head as knitted!), and I will photograph and explain the whole process. Rather than posting the pattern here, I've decided to make a really nice PDF file and make it available for swap.