Thanks for the reply! I'm playing in a progressive metal band (TRANSIENT STATE), and in a live situation we play with a metronome/backing track/MIDI switching system. So freewheeling and improv is not really an option anyways ;)
With my current setup (POD HD to FOH) I'm already limited to play in venues with good monitoring capabilities. The signal from the POD will be monitored through monitor wedges on stage. The tube amp will be there purely for stage sound for myself (in case of bad monitoring) and for the people on the first rows who will otherwise hear no guitar. Key will be to adjust the sound of the POD and the amp so that'll blend nicely! Hunt for tone, right? :)
To be honest, I didn't come up with the idea for this type of rig myself. Check out Monuments' John Browne who does a similar thing using the new Helix and a Dual Recto.