I am coming back to this matter...
I use FLDigi and also MixW, in a side by side test, my experience shows that MixW is better on receiving RTTY and CW . (PSK no difference)
Do you got same result? or am i missing something?

MixW works FSK while FLDigi not ( we need a special interface, or Microham, ...)
Integration of MixW or MMTTY would be very interesting in future.