the difference between a 'super low coefficient of friction 0W20' and a regular 10W30 is about 2%. There's no way on earth anyone would be able to tell the FE differences between oils of similar grades/viscosity based on the composition of their base oil, particularly when take into account all of the variables that affect FE.
I don't doubt there's a difference, but that difference is very, very small and next-to-impossible to measure--unless you're comparing oils of vastly different viscosity.