The greatest sound, tied to a keyboard that the form factor prevents you from playing it well is no better than a great panel layout on an arranger that sounds like poo.

Arrangers are meant to be played, LIVE. Where the buttons are, whether you can easily get to them while still playing is critical. The best sound in the world won't make up for changes missed, timing ruined, and fills and variations in at odd times, because your LH has to travel MUCH further than any other arranger makes you to do basic operation of the start/stop/fill/variation/into/ending buttons.