I think perhaps there's a divide here between those that look to the technology to alleviate their musical boredom, and those that think that it is the PLAYER, and almost entirely the player, that makes the difference.
I'm always interested in major advances in arranger functionality, but truth be told, those seem to come at few and far between intervals, and often come at a disadvantage in some other aspect of arranger operation. Two steps forward, one and three quarter steps back seems so often the norm! But the more you rely on your OWN playing, and the less you rely on a machine to do it all for you, the more easy it is to stabilize your rig, and concentrate on yourself and your playing, rather than the technology you are using.
Push comes to shove, what is the layout of most of the live bands you have ever played in? Bass, drums and a guitarist. For almost everything else, it is up to YOU, and your skills. It doesn't take a state of the art arranger to do that! Bass, drums, and a guitar part... Simple enough for even the most basic of today's arrangers, and no real stretch for even a decade old relic!
The rest? Make it YOU rather than the machine, and you have all the challenge that you ought to need to keep you interested for the rest of your life.
I'm satisfied, content, and enjoying playing! Don't need no new arranger for that!
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An arranger is just a tool. What matters is what you build with it..!