Also about the fit:
1. What's the instep height? High, medium, low?
2. Ankle fit? Better suitable for thin ankles or thick?

I had the same thought with my 27's, thinking maybe I should have went with the 27.5. If you mold the liners, they will fit much much better. The only difference in half sizes is not the shell, but the liner.

For Ada's question. The Dyanfit ZZero 4s' had a very good fit/comfort and uphill performance. They were very nice boots but were a bit stiff for my taste. The Primes have a great fit(I did need to size the Bds' 1/2 size up). They are very comfortable and tour great. I think the flex of the Primes is perfect for my taste.

Tom - How would compare these boots too the Dynafit ZZero 4 C-TF you had? Flex? Touring comfort? skiing performance? Thanks

I just took my Primes out for a brief tour here in Little Cottonwood Canyon. My foot is average width, high instep, skinny ankles. Great fit in the ankle, and arch. I am thinking I may have bought the boot 1/2 size to small as the boot was very very tight in the toe box. I decided to go with a 27.5 with room to break them in but may have to see if I can trade them out for a 28. I should also add that the boots ski very nice.