I also recognize Yamaha and Korg for their use of Mega voices (Yamaha) and DNC sounds (Korg) in styles which has added much realism. When I compare Mega-voiced styles to the non-Mega-voiced type, there is a marked difference in the authenticity, with the former easily equaling an audio style, in my opinion.
I'm quite certain that Korg users would get the same outcome comparing DNC-based styles to their non-DNC counterparts.
I waited for the Tyros4 (although I could have got a demo Tyros3 at a great price) because of the former's ability to use SA/SA2 sounds in the styles.
Ketron has quite likely heavily invested in full audio styles, and therefore must continue to support them (despite the limitations mentioned above), and, it does give the player another choice in how styles are produced (and sound), however, I can't see either Yamaha or Korg (or Roland) going that route.
Yamaha Tyros4, Yamaha MS-60S Powered Monitors(2), Yamaha CS-01, Yamaha TQ-5, Yamaha PSR-S775.