Like RogerP, Reszo suggested doing a bit of wearing to determine fit, and was willing to exchange if they don't work. I went home and gave them a shot and am left struggling a bit. They certainly don't first badly, but the laces fully close right off the bat and there's a bit of heel slip. I'm concerned that this will get worse over time as the leather stretches. So maybe 42.5 would be better, but emotionally I want to stay with the 43 so that I can wear them tomorrow.