That's my main problem, too. Or, was. I was the only guitar player in a band and it was great going into a good PA with 2 XLRs to Dual Amp. (The glorious Plex/JCM combo)
And, like it always is, you write some werid songs, you write some good songs and then you write a song which seems to say "Dude, put some oldschool Iron maiden harmonies in me!"
So the trouble starts. Because of course you want a Gate at the beginning just for "Cleaning purposes", of course a OD Pedal to boost the british amps and maybe a Delay or a Reverb or a Chorus.
Maybe I could have made an extra patch with the harmony stuff where I downsize the rest of effects. But as a singer I tend to keep it as simple and stupid as possible, so I wasn't capable of switching banks inbetween songs, And my main FS 5-8 presets where already my Clean, Crunch, Rhythm and Solo patches. That's where the stereo effect with the Delay comes in handy.
I also works with other Delays, such as the Digital (w and w/o Mod). A nice gimmick there is you can adjust Bass and Treble a bit to your taste, which can completely lift the whole patch up. Or make it even worse :D
What I have yet to try: Meambobbo's style of dual cabinet. I have read about it quite some time ago and came back to it as I saw one of my fav. guitarists live and he was playing the same 2 amps through 2 different boxes (Like you mentioned in your original post). Definetly have to dig deeper in that matter. DSP isn't the big problem anymore because we are now 2 guitarists ^^