What I don't understand is how some ships can have such high max airspeeds without getting RBS. Are their rotors turning so fast that the tips are barely subsonic, or what?
Modern blades for faster helicopters are becoming by necessity more complicated in shape. Westlands ran the "BERP" project (British Experimental Rotor Programme) in the late 70s / early 80s and came up with an "oblique spade" type of tip, which gave the tip a swept wing effect (good for high speeds) whilst minimising adverse aerodynamic blade twist/flex and without sacrificing too much performance at lower speeds. I don't think anyone these days equips a modern medium or large sized helicopter with a simple "plank" shaped blade design.