What is the spin rate difference between a grooveless wedge and a traditional wedge with grooves?

According to a test conducted by Rick Shiels a wedge with grooves creates 12,000rpm and a grooveless wedge creates 6,000rpm of spin.

More about the spin rate difference between a grooveless wedge and a traditional wedge with grooves

Check out the German club manufacturer, Bagger Vance's, grooveless irons and wedges.