It's hard to compare them though since the Jet Fin is shaped like the foot of a cartoon clown, whereas the F1 is shaped like a human foot pocket.
Best description ever!
You should be good to go with the XL. I use XXL for size 13 rocks (heavy insulation) and will use size 12 "Warmers" boots in the same pocket if going wet. The Warmers boot is like a hiking boot...... this is the sizing chart off DGX for them....
[TABLE="width: 596"]
[TR]
[TD][TABLE="width: 200"]
[TR="bgcolor: #666666"]
[TD="align: center"]F1 Fin
Size[/TD]
[TD="colspan: 2, align: center"]US Shoe Size[/TD]
[/TR]
[TR="bgcolor: #666666"]
[TD="align: center"]Men[/TD]
[TD="align: center"]Women[/TD]
[/TR]
[TR="bgcolor: #DDDDDD"]
[TD="align: center"]Large[/TD]
[TD="align: center"]6 - 8[/TD]
[TD="align: center"]7 - 9[/TD]
[/TR]
[TR]
[TD="align: center"]X Large[/TD]
[TD="align: center"]9 - 11[/TD]
[TD="align: center"]10 - 12[/TD]
[/TR]
[TR="bgcolor: #DDDDDD"]
[TD="align: center"]XX Large[/TD]
[TD="align: center"]12 - 14[/TD]
[TD="align: center"]13 - 15[/TD]
[/TR]
[/TABLE]
[/TD]
[/TR]
[/TABLE]