Knock on wood I barley ever remembering a catastrophic failure with an arranger kb...except two times years ago on my old Yamaha Psr9000 the screen display went black but was still working had to finish the gig using a flashlight shined on it so I could still see the display menu with no backing light,.................another time same KB.....I had a worn keystrip Yamaha was famous for those failures you'd know it right away from the Blaring sound when you pressed key down YIKES!!, but with patience I was able to order a new strip and replace it.
All my Ketron units performed perfectly and I had almost every one including modules also.
So my point is no need to "DISS" Ketron they make a professions quality unit for sure. Sure things happen one way or another due to human error on every keyboard hopefully never but all in all most have great track records..