genus9, I think what you're asking is how to reliably pitch bend down or up 4 semitones, yes?
you can set this in Patch > Pro Edit (hit PATCH twice).
Go to Pitch then adjust pitch bend range up / down to +/-4
If you are playing multiple parts and only want the pitch bend to affect one patch, you do this in LIVE > PART VIEW > PITCH and send bend to 0 for any other parts you don't want to bend.
In a nutshell the pitchbend works for a single note only....
I want to play a chord and control the pitchbend i.e. the whole chord down to 4 tones. This way it is in tune.
If you use the method suggested by Artemiy and yourself, suggested then it only works on a single note...I want the whole chord to bend...
The only other way out that I see is to use a polyphonic synth sound with an orchestral or brass multi note patch. Where the one note is multiplied sounding with several similar notes....(i.e. 3 or 4 C notes together)
I would have thought with technology today that the G6 would be intelligent enough to bend a chord...unless I am missing something simple here!