cajun100, sYnergiGS drums are XG compatible and as a soundfont wavetable is of moderate quality. You definitely could test Yamaha styles with it. Also keep in mind you can always exchange individual instruments within the wavetable for higher quality versions using Soundfaction Alive: http://www.soundfaction.com/alive/

I have in past converted Yamaha Pianos in Giga format to soundfonts with very good results. For this I used CDXtract. The good news the system is flexible and you can build it to suit your requirements. http://www.cdxtract.com/feat4.php