Always mono.
At home I use my Stage with a Headrush 108.
At rehearsals I go straight to the desk.
Live, I use In Ear Monitoring.
At home, I make corrections, depending on the guitar, with the output eq.
At rehearsals I first adjust the eq in my channel at the desk. It works.
Live, I have a very nice sound with the IEMs. Our sound man does what he thinks it's correct for the PA and it doesn't affect what I'm hearing.
I must say I don't use a lot of effects and I don't pretend to have a perfect sound in every situation. I just go for an almost raw sound that cuts in the mix. Well, Actually let's say 5 sounds: same kind of amp with different eq and gain levels, some reverb and delay and some wah when I want them.
I'm thinking about another 108 for the double tracker at home, to try it and see if it's ok for rehearsals and live use with my band. There is another guitar player and I'm not sure it is a good idea. If it is, I'd use stereo delays, too.