Let me share what I am about to do. I read and read this forum and got a lot of info on boot fitting and popper choices. I am looking at Head S13 and S11. Let me start with this that we don't have a ski shop in Kansas City that even remotely carries Head. I am coming out of Salomon Xmax 10 ski boots. What I am about to do is usually a no-no, but I am using everything I gathered here plus previous experience with boots.
I am a 36 year old male, 5'9", 170 lbs, very fit,large calves, foot medium width, little lower ankle/heel volume, medium to high instep, left foot measures 264mm, C wide, right foot measures 260mm, slightly wider than C, just a relatively normal foot, wear US 9. Salomons were 26.0, 305mm last, aprox 98-100mm wide, custom insoles.
From research I have found that Head S13, S11 boots can accommodate my instep as well as my large calves. It turned out true. I was in Breck last week and one place carried S11 in size 26.5, 307mm shell. I did try it. Vow how comfortable they felt. That is what scared me. They were either going to be to big or my Salomons are so bad. S11 has 103 mm wide last, and I backed out from buying as I was not sure whether that was going to be to wide. They did not have 25.5 to try, which was 297mm and I am not sure if I would fit my foot in that. Now I am sure I am getting S13 as it comes with 100mm or optional 103mm last. Just not sure if 26.0/26.5 with 307mm will turn out too long or should I try 25.5 that is 297mm.
I tried Tecnica Diablo Magma 26.5/307mm, but my heel would want to come up, so that was out.
So, plan is to get them online, hit the size correct and than visit a shop in the "mountains" somewhere for fine tune and final fitting. The idea here is to get a good initial fit out of the box with little tweaking. Custom insoles will transfer to Head boots.
Any thoughts are appreciated. I know this post is too long, my apology.