Yamaha should add the 2 live control knobs/arpeggiator that's on the PSR E423. (Just bought one for my office at the church.) If this feature were included on the MOTL arrangers, it would add a whole new realm of creative possibilities, especially if it were linked to the arranger engine, allowing you to incorporate arps into songs and recording patterns to the multi-pads. I personally find the 423 an amazing board for its price point. It's a sleeper of keyboard IMO.