Looks like around 3, blade gap measurement wise...
http://wiki.badgerandblade.com/Double-Edged_Safety_Razors_Ranked_by_Blade_Gap
I agree with you. The head geometry is not exactly the sameI learned on a '56 Super Speed then moved on to my '64 Slim. At first I tried to mimic SS performance with the Slim but I discovered that was the best idea...why? They are 2 different razors! Once I started using the Slim to its capability the shaves really took off for me.
Food for thought!