While some people have no problem with it (perhaps a very light touch), I have a horror of features that are triggered by velocity or aftertouch.
How does the keyboard decide between you wanting to 'pop' a note out nice and loud, or playing strongly with eight or ten notes, and thus placing a fair bit of weight on the keyboard, and the intention to trigger the fill or variation change?
I usually feel far happier putting these controls at my feet, where keyboard technique doesn't conflict. Plus, you'll have a far higher choice of actions with a pedal-board, compared to the one action that aftertouch or vel-switch will allow.
Just my 2¢ adjusted for inflation......
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An arranger is just a tool. What matters is what you build with it..!