Is it possible to get two outputs for the guitar: one wet, with effects and one dry, non-effected guitar signal via either the dual XLR or Guitar TRS outs?
Unfortunately not. It's only with the vocals that you can route effected and dry signals out of the outputs. The three Output modes, Stereo, Mono and Dual Mono only change the way the vocals are routed and not the guitar.
You can therefore chose between dry guitar, thereby bypassing the guitar effects completely (by using the Guitar Thru) or effected guitar (by using the XLR or dedicated Guitar TRS outs).