The very first time I heard this Tyros4 demo, I was impressed with the improvement of the brush kit..and I have said so..at the time..
I think the Tyros4 sounds better than any previous Yamaha model...even if only slightly better than the Tyros3...
Unfortunately, when compared to the Korg and Ketron demos provided...the Tyros4 demo doesn't belong in the same room as the Korg, Audya..
The Korg sounds live way beyond the Tyros..and the Audya realism is unmatched..
Now a combination of the Yamaha lead sounds (a few)...)...the swing styles from the Korg, and the arranger sounds from the Audya..would make a great keyboard..but if you could only have one board..comparing these demos...the Audya has the edge over the Korg......just put the Tyros4 back in the box..
Another point when considering cost..the Korg becomes a possible front runner...the Yamaha definitely stays in the box on that count too...