I'll add another two datapoints on sizing for the Comfort Turnout. I am an exact 10D on one foot and a bit under a 10.5C on the other (measured by a Brannock with the socks I wear them with).
Ordered a pair in kangaroo about a year ago in AUS 9F. Comfortable, not particularly snug fit on the 10D foot. Kind of snug in width on the 10.5C, but length seemed okay (albeit "just" okay). I figured since it was a width issue they'd break in okay and be perfect. Didn't happen: as they broke in my foot slid forward over a few weeks and the problem was slightly inadequate room in the toe box. Began to drive me crazy and I had to Ebay them after a month or so.
Ordered a pair in Yearling last week in AUS 9G. I figured going up a width would widen the toe box a bit. Looks like the exact same fit issue. The thicker yearling leather makes the 9G fit identical to the kangaroo 9F (perhaps even a bit more narrow). Initally the fit on the almost 10.5C foot seems like a minor width issue but after wearing them for a couple of hours I can see the same thing happening as before and the issue becoming a slight length problem. On Ebay now
(if you're a 10D, I think they'll end up being a good deal).
My (hard-earned) observations (again for the Comfort Turnout):
- One size down from US to AUS
- G width = D width in yearling, drop a width for Kangaroo (F=D)
- When trying on, keep in mind that the heel on these boots is somewhat higher than you might be used to. As a result your foot will probably slide forward more as they break in. "Just enough" toe room when you try them on will probably not be enough over time.