In order to take advantge of the quality of all effects in the G-Major, it is recommenable to use the G-Major in a serial manner.
If you wish to run the unit in parallel, it would be best to use only the CHO/FLA, DELAY, and REVERB blocks - plus a couple of the algorithms from the PITCH block. The "MIX" control of each of the four effects would have to be turned up to 100%.
Some parallel loops have the ability to run 100% wet, which in reality will mean running the loop as a serial loop.
From software version 1.27, the G-Major has had the ability to disable the dry signal on its output, by way of the 'Kill Dry' feature. The G-Major 2 already features a 'Kill Dry' option.