One of the upgrades I liked most about the Tyros4 from the Tyros3 was the former's ability to use SA/SA2 voices in the styles.
Let's face it, an arranger keyboard's soul is in it's styles.
Most of the T4's preset styles use SA/SA2 them to great effect, as do the Premium Styles, and, of course, with Style Creator you have a lot more tone colors to work with.
I'm still exploring and enjoying even after almost two years.
Ian
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Yamaha Tyros4, Yamaha MS-60S Powered Monitors(2), Yamaha CS-01, Yamaha TQ-5, Yamaha PSR-S775.