Is there enough space to write how I feel about Mainstage? Hands down - AWESOME!!! So versitle and easy to use and the instruments are incredible. Editing and tweeking sounds is a breeze. Not only use Logic Pro and Garage Band, but you can also add other VSTs. Buy an inexpensive USB to MIDI converter cable and connect older Midi synth (my Korg DS-8, 01Wfd, Akai AX60) to combine internal sounds and mix with MainStage is so powerful and inexpensive solution! I love the feel of my old synths and they are more rugged then most USB controller keyboards out today. In fact, I have had four keyboard running from MainStage via USB and MIDI/USB running at one time without any latency! Using the internal sounds from the keyboards mixed with the virtual sounds from MainStage gives you limitless choices to match a sound from a recording your are learning for your next band practice or coming up with very unique voice for your own project. Not expensive, so why not add it to your Mac?
MainStage was one of the biggest reasons I choose to use a Mac. I can easily turn mastered tracks in Logic into a fully playable song/show as all instruments/VTS's available in Logic are in MainStage. I Also use it for all my bass and guitar effects and use it for live looping.
Synth rack, guitar amps & fx, vocal fx, sampler. I use it in sync with Ableton Live 9 through IAC internal midi driver in OSX to automate the scenes changes and on/off fxs or instruments.