The above would be very handy to have.
If you would also give the option to patch bus outs back to input channels, or at least allow free routing of the FX rack units it would make M-S processing possible 
you can select the stereo image options in the preamp
Stereo Image–This section is visible only when a stereo input channel is selected.Touch the mode to select from the following options:L/R = standard left/right.R/L = switched left/right.L-Pol/R =standard left/right with switched polarity on left.R-Pol/L =switched left/right with switched polarity on right.Mono =left and right fed to both channels.L/L = left fed to both channels.R/R =right fed to both channels.M/S =for decoding a mid/side array (outputs M+S/M-S). For normal M/S use, the mid signal/microphone should be patched to the odd channel and the side signal/microphone should be patched to the even channel.The width control can be adjusted in 1% increments from Mono (0%) to Stereo (100%).