Hi Paul --
Yes, we are definitely exploring multi-channel playback. It may take the form of adding support for audio files with more than 2 audio channels, or support for having multiple audio files playable from a single cue, (or maybe both?).
For file exchange, you can export .gobutton and .gobundle files from Go Button 3.x and open them as a workspace in QLab 4 and later. Going the other direction (exporting from QLab to Go Button) is not possible right now. We'd like to figure out a way to do that, but it is a much less straightforward translation since QLab has far more capabilities that don't exist on Go Button.
Brent