oleg7, you presented another very good alternative. The same thing applies here and that is the drums will need to be modified either in the sampler or the Yamaha styles. Yamaha has chosen to be unique at the expense of customer satisfaction.
As far as quality goes, you can achieve very high quality by converting premium voices to Soundfont. The drawback is the Wavetable gets very large very quickly. I have done some of it for instruments of critical importance to me, e.g., piano, sax, trumpet, etc. If I wanted to, I could convert my Giga 500 MB GM Wavetable (GM500) to Soundfont (or other format) to use with my auto accompaniment only. I would still keep using my premium voices with Kontakt for my lead/melody parts.
While I have not tested it, Halion 2.0 may present another very high quality GM Wavetable solution. Sonic Reality may be another more moderate quality possibility.
[This message has been edited by Frank L. Rosenthal (edited 10-12-2003).]