The 1 MTO is because I wanted a Monk style boot instead of the lace up, so had a Arran modified.
I wanted a slip-on that may pass casual inspection as dress shoes. So had a medallion-less Chester made.
Unfortunately I do not know all the various elements I can change on a MTO, since I went to the process with just those criteria. I am sure Nick will be more than happen to tell you all the things you can change in an MTO though. He is really a pleasure to purchase from.