I'm a home player, so all I have is a soft bag. Flying, I wouldn't even attempt to bring a keyboard. Maybe as checked baggage, but that means an expensive hard case (and a lot of weight!)

If I do a vacation car trip, there will be a lot of other stuff in the car. I would like to put the arranger in the rear hatch where it would be out of the sun, and importantly, out of sight!

I'm sure the BK5 is the best choice for this because it does everything I want and I can probably use the same UPGs on the BK9. Now I just have to trade with someone, or find one in good condition for a low price!