I played a Tyros 5 last week for maybe half an hour. I think there is real improvement in the sound and it does not seem to be related to e.q. adjustments. I opened the mixer page and set it everything to flat and it sounded really good.
The styles seemed to have been reworked pretty extensively.
Bear in mind most of my experience was from playing S950, so the T4 SHOULD sound a lot better.
I noticed on the e.q. page they had a slider for "Volume". When you raise it all the e.q. bands were boosted to the new level.
This should help people remember that boosting all the e.q. band levels is merely turning up the overall volume. E.Q. should be subtle and, if necessary, use a curve centered around the Zero line, if that makes sense. If you have five bands and boost them all, you are just turning up the volume and taking a chance on introducing noise and/or overdrive.
Sermon over. It's a great keyboard and maybe a better incremental upgrade than the usual Yamaha new totl models offer.
Oh, I was not tempted to buy one.