1) Don't give too much importance to my comparison between GP-10 and GR-55. I mean, GR-20 has a little set of pre-made sounds with few possible editings, GR-55 improved this condition by including PCM Synthesis which is model based (pre-recorder base sound to be threated with a simil-synth architecture). GP-10 is the first one who let you start building your sounds from 3 oscillators like in the most common subtractive synthesizers architectures. I think it's just a matter of taste.


2) Most of the time i only use a wireless jack to connect to the Godin XTSA to the helix. When i need Synth functionalities i connect the 13pin cable.



3) Something like that :
Helix Send 2 -> Guitar IN GP-10
Mono OUT GP-10 -> Helix Return 2


FX-Loop2 Block is used as the Synth sound. Eventually, if you are using only the 13pin cable you can connect as follows:
Guitar OUT GP-10 -> Helix Guitar IN