Can't update that polyphony, or the sounds (USB or HD sample loading is still glacial, not practical for a live show), or the outdated engine (newer ones tend to be faster, less latency) though, so I would tend to say, either a PA800, or wait until they bring out a new model PA1XPro using PA800 engine.
The color touch screen, if as good as the Rolands, is easier to use than the PA1X's, and in truth, the PA1XPro is just getting a little long in the tooth. Korg have all kinds of exciting goodies in their new workstations, you are going to kick yourself if they bring out a new 76-er with some of that technology.
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An arranger is just a tool. What matters is what you build with it..!