I send my X4 signal using the 4 audio out option to one side and expand it. I send my VoicePrism R&L signal to the other side and do not expand it because some of the VoicePrism presets are degraded when expanded. This may be another reason to consider the 200 over the 100.

The blend seems together even if the VoicePrism is not expanded. (I found with the BBE Sonic Maximizer that when I sonic maxmized the X4 accompaniment and not the right hand that the "band" sounded like it was in 2 different rooms.)

I found when I ran my vocal through the X1 (I used the X1 before the X4 came out) and its harmonizer that it seemed to get buried in the mix - it was audible but not up front.
Glad to hear you don't have that problem with the Tyros.

Good Luck!

RJM