Blueberry - if you're really within a size, think about it!!
Here's the thing -- these are a medium width and NOT a sloppy fit at all. The Boa lacing system gets them as snug as you want them...so with a nice thick sock, you may very well be in good shape!! So for example if one wore a 42 or even 41 Sidi, these could work really well with a good winter wool sock and/or medium weight sock w/ liner. I wear a 43 Sidi, and got the 44s in this, and honestly could get away with a 45 in the Lakes if I wanted to go to my Smartwool mountaineer weight socks...
Sit bones = ~135 mm, saddles that work ~ 155cm/6.1 in wide
2003 da Vinci (custom road/all-rounder)/Terry Butterfly Ti
1994 Gary Fisher Nirvana (vintage MTB/commuter)/Terry Butterfly Chromoly
1991 Terry Symmetry (NOS frame/fork, project in progress)
1973 Raleigh Super Course (project in progress)