I have bought the BK5
Styles are good but most right hand sounds are cheap.

BK5 is cheaper than BK7 and have a keyboard, so for me it's better.
You can play missing BK7-m styles on the BK-5.

I can almost play BK5 styles with vArranger and Ketron SD2. Some styles are very well played by pro musicians !

Roland styles are well balanced and efficient. Less drums in face than Ketron styles, and less smooth studio-like as Yamaha styles.

For the price it is a good KB ! you can load any Roland styles from USB thumbs, and you can create you own style.