The abrasive tests for the EH-101 prove more about the behavior of the airfoil used than they do about anything else. Those tests showed that the airfoil is particularlt sensitive to roughness, and that they therefore stall earlier as a result. Those control forces are the direct sign of early stall and high pitching moment due to the stall. A laminar flow airfoil is particularly sensitive to roughness. Most helo airfoil sections are not laminar flow because roughness, bugs and icing all are unavoidable.
The downward anhedral tip on the Sikorsky 3rd gen (S-92) and 4th gen blades are specifically to control the tip vortex and create extra lift at low speed without adding drag at high speed. They add between 5 and 7% more hover performance to the aircraft.
I flew the first flight on the Black Hawk with the S-92 blades ( the combination that is now on the UH-60M) and the blades allowed at least 1500 pounds of increased performance at the same engine power (even though they had 16% more chord, which should have reduced hover performance if other factors were equal), as well as adding about 15 knts to Vne (mostly due to the extra chord).