I would check carefully that those FP Roland’s had the ‘Pianist2’ mode. Up until the BK series, Roland only ever had the ‘3 notes for a new chord’ system whether the sustain is down or up, and trust me, that system is FAR harder to play normally with.

I seriously hope all manufacturers add that Pianist2 mode to new arrangers, maybe even tweak it a bit to allow the player to adjust whether you want four, five or six notes. It makes a radical difference to whether you need to adjust your normal piano technique or not. Most of the time, I can play pianistically without having to think about the chord recognition at all…

The old system makes you adjust your playing a LOT.

Combine this with the BK-9’s Dynamic Arranger feature (sadly, not on the other BK’s) that adjusts the dynamics of the style to match your dynamics and it truly is quite spooky from time to time how well the backing follows your playing!