Try adding for example a big stereo reverb to a profile with high decay time and keep it wet enough, you'll notice that :
-the reverb with master left output it will sound louder and with more frequencies
-the reverb with master mono output will sound weaker = phase cancellation
Master mono output is actually creating phase issues with stereo FX modules.
I never use a lot of reverb live, so I didn't encounter that issue. I meant stereo time-based effects like flanger and chorus. There is no option to select mono or stereo versions, so I wondered how this is dealt with.
