Yamaha's business model is to make mild or slight improvements on the next model with just enough to tempt their customer base to change up and purchase the latest model. They ensure That the product is limited so that it cannot accommodate third-party products only the proprietary Offerings which Yamaha charge through the nose for. I'm not criticising Yamaha for the business model. It works clearly. Yamaha simply have understood the market, they understand who they are selling two, and they understand the triggers that will encourage its market to buy the next model up. No doubt Yamaha have twigged onto the idea that its customers will buy a new keyboard every year or two And inject a new cash supply for Yamaha's boffins to tweak the next model Which has probably been lying on some technicians desk for the last year already been on the .That's just clever marketing.