I had a BK-5 for awhile and found it somewhat cumberson to get around to various patchs and rhythm patterns because of the way the menu screens were laid out. I think it had more to do with my lack of experience using the BK-5 rather than any short comings of the instrument itself. I didn't keep the keyboard.

I bought a Roland Prelude and am much happier with the instrument sound wise and with the menu setup. Internal speakers is a feature I really like.

It's all rather subjective.

However, I am getting the new Roland BK-9 in a few weeks. So much for my criticism of the BK-5 huh?