So, in our case, which could be the best option? I've seen the apogee Symphonic Mobile System but it's completly out of our price range.
Basically, we will use mainstage for using the built-in plugins -Ultrabeat patches- as well as some AU's that we use a lot (mellotrons, soft synths...) and also apply some effects on different sources (for exemple in one song the guitar will have a lot of reverb and, as I said, in other one we could loop a chelo).
We were about to use Ableton Live for those purposes, but I think we could get more used to a Logic-based enviroment as we recorded everything on Logic (and we have a lot of sounds and presets coming from it).
I don't know exactly how our main set could be, because each of us use different gear in every song... but does it mean that everything should be pluged all gig long? No idea... We won't really use mainstage effects/midi knobs in all instruments all the time, but it's true that we really need more than 2 or 3 different sources, and maybe duet it won't fit for us... so which audio solutions should we buy? We also have an iMac but I think we should stick on the macbook as we are going to be a long time on the road.
If it helps, I think we will use mainstage basically for:
-Droping backing tracks. (also i would like to know if MainStage has a similar feature to Live's Warp engine, so we could tap a backing track and drop it on that-day-live-tempo without pitch issues or everybody slowing/speeding up to adjust to the backing track original tempo.)
-Change between different midi instruments (piano, mellotron flutes, synth Bassline...) with a simple touch of a button on my edirol PCR-50
-Apply loops to real instruments (guitar/voices/chello) and fx -distortion or delays).. not more than one at a time, but, as I said, coming from different sources -we could change jacks between songs but it could be a completly mess for the guy on the desk-
-Vocoder controlled via midi keyboard.
so, once again, what should be our best buy?
I think in the next album we would do everything with an accoustic guitar and a pair of maracas... seriously.