we have a 920, and have replaced the old Volvo 18 hp. with a Yanmar 30hp. During the upgrade, we added a 3 blade Gori folding propeller and new propeller shaft. New cabling throughout the engine bay.
The extra Hp. is a definite advantage, particularly during docking. There was little weight gain and fuel economy has not altered a great deal. 1.3ltr / hr. now 1.8 ltr / hr.