I really wanted to add Mega voices to my rig, but the incompatibility between MotifXS Mega voices and T2 and S900 ones makes using the XS Rack as a replacement for those products very difficult, and with no sampler, it starts to be a far less attractive purchase.
You never know though. Maybe Yamaha "fixed" the SAV implementation with the Rack XS compared to the Motif XS. I believe though that the Mega Voices are all the same in the Rack XS, T2, and S900. At least as far as the technology behind them goes that is.
The S900 has less in quantity of the mega voices than the T2 or Rack XS does though. But there should be no incompatibility as far as using the Rack XS with the S900 or T2 in my opinion.
What you need to be aware of is if you have another brand of keyboard product other than the Yamaha brand and you try to MIDI up to the Rack XS you will most likely face incompatibility issues with not only the Mega Voices on the Rack XS, but also the SA voices on the Rack XS as well. I know I had problems when I midi'd up my Roland Sonic Cell with my Tyros. Since I bought the Roland Fantom G I am now using my Sonic Cell with that instead of my Tyros. Of course with that combo there is complete integration and compatibility.
But the Motif Rack-XS used with a non-Yamaha i.e. (minus Mega voice and SAV inside) product?? There's bound to be some compatibility issues in my opinion. >> Your mileage may vary.. And all I can say is buyer beware!!
PS: I'm talking about when you play SMF on your keyboard through the Rack-XS. If you play the keys while playing the patches i.e. "voices" in the Rack XS you should be fine. Except that you can't play the Mega Voices in a live venue type situation as we all know.
At least not effectively anyway.
Again, your mileage may vary, depending on how well you can play those nefarious Mega Voices, of course.
[This message has been edited by keybplayer (edited 07-08-2008).]