I don't know for a fact. But I'm pretty sure my BK doesn't output NTA as such through MIDI.

However there might be a workaround. If the LEFT and Chord zone are the same, at the risk of burning a little polyphony you could activate the Left voice with a volume of zero or one. And those notes are something you could designate to be transmitted via MIDI OUT.

I've never tried adding looping specifically where you record a chord progression, and then play it back immediately after. But when I had my Roland and Yamaha arrangers MIDI'd together, I did use a sequence of triads and tetrads stored as a MIDI song on the Roland to drive the accompaniment engine on the Yamaha. With appropriate Mark and Jump points it was very convenient, and if I wanted to play the chords "live" I could select a different registration and easily do so.

Years later I'm sorry that I took that setup apart. With my favored Roland chord recognition, Roland's mark and jump plus score display driving the huge library of Yamaha styles (and style editing parameters) it really was the best of all worlds! I remain convinced that by MIDI'ing two arrangers together there is a net gain of function-- you can do a lot more than you could with either one alone.