The new BK-9 and the Korg PA900 both have a Chord Sequencer. Only the Roland allows you to save and load them, though. Thing is, you can record these as slowly as you like (slow the temp WAY down!) to account for your disability (or use your RH), then speed them back up when you use them to play.
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An arranger is just a tool. What matters is what you build with it..!