Finding the reasons why Yamaha does not make 76 note TOTL and MOTL arrangers, would be just as likely as learning the reasons behind why Roland stopped making the 76-note G-70 and E-60 arrangers, but still stayed with 61 notes for the new Prelude/GW-8.

Only those inside the companies know those answers and reasons, and anything else would be mostly speculation.

Ian
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Yamaha Tyros4, Yamaha MS-60S Powered Monitors(2), Yamaha CS-01, Yamaha TQ-5, Yamaha PSR-S775.