The Motif ES is the second non-arranger keyboard to feature chord recognition (an essential feature of an arranger keyboard). The Karma was the first, to my knowledge. However, while the Karma had very sophisticated (if imperfect by Scott Yee's standards)chord recognition, the chord recognition on the Motif ES may be very limited. Bear in mind, the Motif ES is not available until October. The manual is available on-line, but it is not clear on chord recognition.
From the Motifator forum, it appears that chords must be entered in root position. The chord recognition distinguishes major 3rds from minor 3rds, major 7ths from minor 7ths, and augumented and diminished 5ths from perfect fifths and adjusts an arpeggio to fit the corresponding scale. This means that chord progressions will be plagued by parallel fifths--which can be musically tedious.
OTOH, each voice or performance can have 5 arps assigned that can be switched using buttons, sort of like the four variations in a modern Yamaha style, I guess.
So, IMHO, the Motif ES comes up short as a quasi-arranger. It's too bad, because it does offer your choice of 61, 76, 88 keys, digital connectivity, vocal harmony (with plug-in board, huge sound library with mega-voices for guitar and bass, triple-stike piano, and on and on.
I am speculating somewhat, because I don't know how the Motif ES responds when presented with an inverted chord. BTW, I started a new thread because the previous Motif ES thread was taking on a somewhat negative tone.