Thanks Dunedin,
I thought that by panning the signal hard over, the left and right the XLR outputs would each give a mono output i.e. hard left output to left XLR and vice versa, wouldn't the output only be stereo if both XLR outs were centred and feeding two separate outputs , I wouldn't be expecting both guitars to be played at the same time as you do with your band.
Please feel free to shout if I'm missing the point