Just got my Trio+ today and was thinking the same thing... as a quick fix I ended up using two guitars and two signal paths. Not really efficient, but it worked for my needs. I hooked the Drum/Bass Mixer OUT to my PA mixer, had the guitar OUT going to the Guitar INPUT on the Helix, and ran this into path ONE.... Output to the LEFT XLR set to L/R on the mixer. Then ran my L6 JTV Variax input to the 2nd Path as the input and had another amp/effects set up, set out to the RIGHT output, again, L/R on the mixer. So the loops were clean and going into the top (path 1) and then I could solo or noodle over the top using my Variax through the bottom path (path 2).
Like I said, not really elegant. But it got me started to see that this device with the Helix is a really fun set up.
I'm def going to check out the links above - thanks for sharing!
Cam