Yes, they're completely different animals, but that's the 2 boards I am now considering for our church music ministry. My keyboard player wants more than 61 keys, otherwise the T2 would be great. So I am considering the S90ES as an alternative. It's not nearly as complicated as the Motif, but still has great sounds, including MegaVoices. It lacks many of the features of the T2, however, such as a good screen, and a decent sequencer. It will play MIDI files via the USB. (I don't know if one can tweak those files to play the good voices in place of GM voices).
In the end, the S90ES would be limited in its versatility, but will make my keyboard player happy, and the T2 would open all kinds of doors to creativity and would make me, the minister of music guy very happy!
We'll see how it all pans out.
Tim