I can give it a shot, in my DT 1466 socks my brannock is 10.25E/10E L/R: I take a 9.5EEE in the 65 last but a 9.5EE would do if I didn't have to take into account my combined moderately high arch and instep; I take a 9EE in White's MP last and it fits pretty great overall; in both cases the shoe flexes at my arch and the taper is about the same with the MP being slightly more aggressive while having a shallower toebox.Don't mean to inturpt the serious talk but...
Anyone have fit comparisons between Allen Edmonds 65 last and White's MP last? I am interested in the Otto derby. A customer service rep at White's told me they can make them in EEE widths, so I'm really considering a pair for work.
If I had to quantify the differences I would say that the MP's have about a ¼" more space along the arch/ball and maybe a ¼" more generous instep, the 65 last runs a ¼" longer and hugs my heel a bit better.
Sizing was done in a pair of Fifth Avenue's and Kinney chukkas in suede.
Hopefully that was of help to you.