I'm guessing that the 1/4" jacks in the master out section are just a physically connected duplicate of the XLR jacks, so this suggestion is probably not possible.
It would be great if it were possible to turn the cabinet emulation off for the 1/4' jacks only, which would allow for stereo connection to a amp and stereo cabinet.
The XLR outs in the master out section could still be sent to FOH with the cabinet emulation on.