So I have a pair of suede chelseas on the rain last in 9.5UK, and a pair of black calf jodhpurs in 9.0UK. The jodhpurs fit significantly better than the Chelseas, as I have to wear them with really thick socks otherwise my heels are slipping all over the place. So sizing down was best for me, but I think it might be because my heels aren't particularly large (whereas my instep is).
At this point I'm pretty sure the Carmina lasts just don't work very well for me. Enzo on the other hand fits fantastically. I have a pair of suede jodhpurs, black shell longwings and suede wingtips on the 363MOD, a pair of spectators and black oxfords on the 804, and a pair of button boots on the 74945 and they all fit extremely well. Perhaps the best fitting footwear I own, the only other pair that might give them a run for their money are my G&G Thorpes.