Yeah it's great. I actually misspoke, I'm using the 1 Dub setting for the standard double tracking sound. I decided to permanently mount it in my rack so I moved my GLXD14R and Furman to the bottom so I could velcro the pedal in the back.
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I also discovered that the mono/L output is just the identical dry input, so instead of running my left dry through the pedal, I just connected Out4L to the L input of the pedal, and the pedal's output R jack into Input 4R (set to "Right Only" in Axe-Edit's setup menu).
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So with this setup my left amp is my original and my right amp is the "double tracked" amp. If one of the patch cables or the pedal itself fails, I only lose the right amp, and all I have to do to get it back is bypass the In 4 block.
I couldn't hear a difference between this setup and running both left and right through the pedal so I figured why not just keep the left channel inside the AX3, less stuff to fail.