Question I'd like to be able to use two different drive pedals (or preamps)  in the analog loops and pan one to the left output and one to the right.  Is that possible

Answer The signal flow in the G-System loops is MONO and serial so there is no way to Pan the signal in the loops. (the signal becomes stereo after insert return) If you are going to use the  Drive pedals per preset ,  it is possible to route the output of G-System either to the left or to the right, by muting one of the outputs. So if for example you have Drive (preamp) 1 in loop 1. Drive (preamp) 2 in loop 2. In preset 1, you can bypass loop 2 and  mute the right channel and have Drive 1 + effects in the left channel only, or Drive 1 + stereo effects in both channels.In preset 2 , you can bypass loop 1 and mute the left output and have Drive 2 + effects in the right channel, or Drive 2 + stereo effects in both channels.