I have a 2014 Merc 90 4stroke with say 20-30 hours on it and its been perfect… but that’s minimal time. Also they redesigned the motor for 2015 its lighter with more torque and also is bigger 2.1L? I have nothing against merc but if the price was the same and I could pick I would go yammy purely based on the positive reviews most people seem to have of them, I think in the last few years both have really made quality products and 4 strokes are being perfected by both manufacturers.