About the only REALLY significant improvement in the PA2X, IMO, is the doubling of the polyphony. Oh, and the new piano, but you can load that into a PA1X if you want.

But Korg have already acknowledged that, for many of the 'Guitar Mode' styles, you really need that extra polyphony. No doubt, any future styles will be voiced with this in mind. So, for future-proofing yourself for the next few years (Korg are exceptionally good at providing OS updates to add newer model features to older models), I think I would have to recommend going the extra expense and springing for the PA2X, if you are looking for a 76, or a PA800 if 60.

Polyphony is just one of those walls you can't break down.. and will only become more of an Achilles heel as you start to use stereo samples in the sampler, which also is much improved re. it's max RAM and load time. It's funny how probably the most IMPORTANT improvements are the ones trumpeted the least by the manufacturer. Or maybe, do they KNOW we just respond to the glitz, and couldn't care less about about the engine under the hood?