Here is my personal experience with the 101 and 102 last. I have a high instep, so I will do my best to explain my current lasts and DC Lewis experience. Because of my high instep, so I usually have issues with width at the waist of a balmoral. I usually wear an 8.5-9 US, depending on the maker. To further explain, if the shoes has a high instep, I can size down to an 8.5 (or UK/EU equivalent) I wear 8.5D on the Barrie and the Trubalance in Alden. I wear a 9D in most AE shoes. I wear a 7.5E (UK) on the C&J Handgrade. I go down on this last due to the instep height. In Edward Green, I wear a 8.5E (UK) almost across the board (888, 88, 82, and 32) except the 202 last, which I wear a 8.5D (UK). In Vass U-last, I wear a 41.5. I also go down in size on this last because of the very high instep. On the DC Lewis 101 (chiseled last), I wear a 9D (US), and it is one of my best fitting shoes. It was just a hair snug at the waist on my first 2 wears. After I broke it in, it feels great. The shoe has a standard instep height, hence the reason I wear a 9D in it. I have been wearing my Porters in rotation every other day for a couple of months. I did this to get an idea on fit and comfort over time. On the DC Lewis 102 (round toe last), I also wear a 9D (US). This shoe was a little tighter in the waist, but it also feels great after breaking in. It started a little tighter than the 101. We have gotten other feedback that the 102 is a hair tighter at the waist. I would recommend that if you are generally narrow to standard, you should wear your standard US size. If you tend to be on the wider side of standard, you may be best to size up. David also wears his standard size on the 102. We did have a reviewer that needed to size up. Please remember that we will take returns for fit issues (see terms above).
So, if I wore an 8D in AE last 5 (e.g., Park Avenue and Strand), would I wear last 102 in 8D? Porter in navy is tempting.