This may be a good solution:
Equipment required:
Diezel amp
GCX Audio Switcher
GCX Ground Control Pro
Decimator Pro Rack G
two TC G Majors
Guitar -> GCX Audio Switcher
GCX Audio Switcher Loop 1 -> Decimator Pro Rack G
GCX Audio Switcher Loop 2 -> First TC G Major (used for Compressor,Chorus,Phaser,Flanger,Octaver,Whammy,Detune,Vibrato,Tremolo,Wah)
GCX Audio Switcher Loop 3 -> Diezel Herbert Input
GCX Audio Switcher Loops 4 to 8 -> NOT USED
Diezel Herbert Parallel Loop -> Second TC G Major (set to "KILL DRY"; used for delay, reverb, harmonizer, detune)
With this setup, there is true-bypass whenever effects are not used. The GCX Audio Switcher allows the First G Major in front of the preamp to be completely bypassed. The Second G Major is in the Parallel Loop and set to "KILL DRY", so there will be no tone loss in the effects loop.