The PA2X is a WS from ten to fifteen years ago, Ian. It doesn't sport ANY of the features that are commonplace in modern WS's. No arpeggiators, no Karma, no audio loop slicing and matching and triggering, no audio multitrack recording, no REAL flexibility in part assignment, no rally contemporary drum sounds...

Trouble is, the way I see it, ONLY an outsider can bring off this mythical hybrid, because the current crop of slackers are already making too much money off having the lines separated. Want BOTH, you GOT to buy both...

Maybe Casio, the outsider on the inside, could pursue this, as it has little to offer either side at the moment, but anyone smaller has a big problem developing the content this would need. After all, for all the apparent difference between the lines, it is still the CONTENT, the sounds AND the styles and arp/loops that come with them that sell them off the shelves. Try selling one without any, you'll quickly see that WS users are as needy for high quality OOTB content as arranger users are...
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An arranger is just a tool. What matters is what you build with it..!