I glanced at the manual. It appears the FX Send jack is pre internal FX unit. But I did see anything about tapping Fx Send or Return causing the internal FX to shut off, which is what is was implying with "by-pass/cut-out". So you might be able to blend external FX with internal FX if they happen to be parallel. ( Not the topic of this thread of course.) I do see how this could be minimally useful to blend them. Perhaps add external reverb to internal delay or something. But then that's going to affect every channel.
To answer part of the OP question. I don't think you need a different mixer. If you did you'd have to go significantly bigger to get separate aux sends and more switches for Pre/Post and Channel Assigning sort of functions. Personally, I just don't find all that very useful for a solo artist or small band that runs sound from stage or solo studio technicians making home brew music.


Does the noise in your head bother me ?