Got my Marlows today - the 12D fits perfect in the length, but it's slightly wide. I also have a low instep, so as you can see in the first pic here, the laces are pulled all the way together in order to get them to fit tight enough. I think if I stick a tongue pad in there, it should be a little bit better. That's probably the best I'll be able to do with these though, since the 11.5 would definitely be too short in the length.
Also, it appears that someone may have tried these on in the store before they were shipped to me - either that or they got scratched by someone at some point....you can see the marks on the right shoe in the first pic. Is something like this easy to buff out? The cordovan isn't actually scratched into the leather, it just looks like scuff marks, so hopefully I can polish these out.