I've recently replaced my 66 inch GSC three blade on my 582 for an IVO.
The figures speak for themselves;
GSC
Static 6200
Climb 700 fpm
Cruise (5200 rpm) 68 mph.
IVO
Static 6200
Climb 900 fpm
Cruise (5200 rpm) 83 mph.
Mk 3 with C box. All figures quoted above are solo.