General consensus is to size up for MMM GAT, .5 size if you have normal feet and 1 full size if you have wide feet.
CP: 40.5 (Usually just size down to 40)
MMM: 41.5 (Usually just get the 42)
Lanvin: UK 7
I have a couple TTS GATS and they fit fine, but generally start to hurt the top of my foot due to their constrictness if I wear them all day.