just for clarification, when you say yamaha, are you talking Tyros 2 or an older model??

The T2 is the Yamaha I'm most familiar with the sound of.

Please don't get upset with me just because I prefer one kind of sound over another..... I am sure with enough time and care you can get the T2 to sound pretty much the same as the Rolands and Ketrons, etc., but the OOTB sound of an arranger is usually the basis for the styles. Yamaha would have a problem if some of the styles 'popped' out in your face, and others didn't.

Most manufacturer style 'houses' tend to make all their styles at least 'fit' with each other, a philosophy emerges about whether there will be lots of room in the style for the player, or whether the style sounds fairly full, and only needs a melody... Things like that (though they can be changed with third party styles) tend to give the overall impression of an arranger, at least for me.

And, from what I read on SZ, quite a few hear the same thing as me.... Overall, the T2 sounds 'polished' and CD-like, and Roland and Ketron sound more 'live'. There are exceptions to all impressions, but the overall feel I get from the T2 is of an arranger that goes out of it's way to play as much as it can for you (with amazing quality, no arguments there!), but doesn't often fool you into thinking there is a drummer right next to you.

Just my opinion, YMMV, Objects in mirror may be closer than they appear, Yada yada yada.......